Genetic
Considerations and Breeding Programmes
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- For all species with a managed breeding programme (EEP,
SSP etc.) the
species manager/studbook keeper should be contacted for recommendations
for breeding.
Breeding programme aims and priorities
Alongside
efforts to preserve endangered species as self-sustaining wild
populations, captive populations may be vital to ensure survival of some
species and for preservation of genetic diversity. (B115.9.w13)
Breeding programmes in zoos may be carried out to develop and maintain
self-sustaining captive populations in order to allow continued exhibit of the
species, or to conserve species or gene pools whose continued existence in
the wild is doubtful. (P97.1.w34)
Priorities of breeding programmes vary depending on the starting
population and the aim of the programme.
- Reproduction
should start with a pair or group (as appropriate) of genetically
unrelated animals. (B438.24.w24)
- In species with very few founders, breeding programmes should aim to
maximise reproduction, expanding the size of the population as rapidly
as possible. (J23.27.w3)
- This reduces loss of genetic diversity and minimises the risk of
genetic loss through founders not breeding, or through loss of the
population due to disease, accident, a distorted sex ratio, a
small number of non-breeding females etc. (J23.27.w3)
- Populations numbering less than 50 (or even 100) are
particularly vulnerable to crashes due to disease, distorted
sex ratio, natural disasters etc. (J23.27.w3)
- Genetic diversity is important; genetic variation within a
population is the basis for change within a population, allowing
adaptation, and in an individual, the degree of heterozygosity and
avoiding homozygosity of deleterious
genes is important to maintain
fitness (survival and fertility). (J23.17.w8,
J23.27.w3, J54.5.w1)
- For short-term captive breeding prior to reintroduction. (J54.5.w2)
- Rapid breeding of as many offspring as possible is required. The
captive population ideally should be held in an environment
similar to the natural environment (or similar to the environment
into which the animals will be released). (J54.5.w2)
- Selection should be used only to select against outliers,
reducing the genetic load [of deleterious alleles]. (J54.5.w2)
- For long-term management of endangered species in captivity. (J54.5.w2)
- The aims are to maintain a viable population, preserve as much
as possible of the genetic variation, and preserve the option for
future reintroduction. (J54.5.w2)
- Management should aim to equalise founder representation and
maximise effective population size. (J54.5.w2)
- Selection may be required to control the genetic load. Culling
to achieve this may be in conflict with maintaining equal
representation of founders; culling of outliers may be delayed
until the population size has grown, to ensure that the genetic
loss from the culling is not greater than the genetic gain from
removal of outliers. (J54.5.w2)
- It may be necessary to allow some adaptation to captivity (e.g.
improved survival and breeding) but this should be minimised,
limited only to what is essential for the captive population to
survive. Some inadvertent selection for adaptation to captive
conditions may be inevitable. (J54.5.w2)
- Selection for genetic diversity should not be carried out;
genetic diversity should be maintained by maximising the effective
population size and maintaining equal representation of founders.
(J54.5.w2)
- It has been suggested that captive breeding programmes should
aim to retain 90% of the average heterozygosity of the founders
for 200 years. (J54.5.w1)
- Maintenance of as much as possible of the genetic variability
present in the wild gene pool requires both deliberate avoidance
of inbreeding and demographic management of the population to
establish and maintain a stable population. (P97.1.w34)
- Variables to be considered include: the number of generations
over which it may be necessary to maintain the captive population;
the age and sex composition of the breeding population;
age-specific and sex-specific fecundity and survivorship; the size
of stable population required (based on known life history
features); the carrying capacity of zoos for the species;
requirements for surplus individuals; and how practical it is to
develop controlled breeding or mating. (P97.1.w34)
- Accurate record keeping is required. (P97.1.w34)
- A breeding policy needs to be explicitly formulated and agreed
by all parties concerned. (P97.1.w34)
- Animals need to be of known origin, with pedigrees preferably
traceable back to the original wild population. (P97.1.w34)
- The age and sex structure should be defined, and the number of
animals preferably should be chosen based on the breeding
strategy.
- "Explicit definitions of the need for introduction of
new wild stock should be made in terms of breeding strategy and
breeding management programs with a view to maintain some defined
level of genetic variability in the population." (P97.1.w34)
- Data collection and data sharing are vital; ISIS can provide
census and vital statistic data, demographic projections,
pedigrees, studbooks, and data for analysis of breeding
relationships including calculation of inbreeding coefficients. (P97.1.w34)
- For a maximally efficient genetic management programme, it is
important to remember that the effective population size will
determine the rate of loss of genetic diversity per generation.
Given the use of a maximum avoidance of inbreeding scheme, the
size of the effective, rather than the actual, population, depends
on equal contribution by all members of the population to the next
generation, i.e. equal family sizes, and an equal number of males
and females breeding - for species where social organisation does
not match this, management (e.g. rotation of breeding males) is
required. (P97.1.w34)
- The tendency to favour individuals which do well and breed
well in captivity must be avoided to avoid selection of
captive-adapted, inbred strains. (P97.1.w34)
- From a given pairing, selection of offspring to contribute
to the next generation must be randomized, avoiding selection
based on unconscious preferences. (P97.1.w34)
- Where the aim is to maintain populations purely for
education/exhibition, selection should be used to control the genetic
load. Selection can be used also to select for classic phenotypes,
ensuring animals on display are representative of the typical wild
form. Moderate selection for easy management and maintenance (e.g.
tameness, willingness to breed in captivity, adaptation to inexpensive
readily available diets) may be useful. (J54.5.w2)
- However, species considered common may change in conservation
status, so that captive populations may become of conservation
importance in the future. (J54.5.w2)
- Selection of zoo-domesticated stock probably would result in
unrepresentative animals not suitable for life history studies or
for development of data suitable for use in managing the species
in the wild. (P97.1.w34)
- Zoo-domesticated, inbred strains would be at high risk of loss
of vigour, viability, growth rate and fertility, and could
therefore become extinct. (P97.1.w34)
Preserving genetic diversity and avoiding inbreeding
- As a general rule, inbreeding is to be avoided. Inbreeding occurs inevitably when
the population is very limited in size, as may be the case for endangered species. In
these circumstances, studbooks may be kept and pairings made to minimise inbreeding. Some
species are known to have fallen to very low numbers and recovered without any indications
of problems arising from inbreeding. In others, infertility, poor
hatchability (in birds) and poor
survival have been noted and thought to be related to inbreeding.
- Inbreeding is used in domestic animal breeding in a controlled manner when breeding to
"fix" a particular characteristic, such as an unusual colouration of
pelage. When used for this purpose (which is not appropriate for
conservation purposes) the risks of also enhancing undesirable
characteristics should always be considered.
- In a few species, populations have descended from only a few
individuals without any apparent deleterious effects (e.g. Anas
laysanensis
- Laysan teal, Elaphurus davidianus - Père David's deer), however these should be taken to be the exception
rather than the norm. (J23.17.w7)
In general, inbreeding results in inbreeding depression with reduced
fertility, fecundity, lactation, viability, growth rate etc. (J23.17.w8)
- Inbreeding depression leading to reduced fertility can quickly
cause a small population to become extinct. (J23.17.w8)
- Inbreeding depression may be more likely to arise with animals
which were previously outbred rather than those with high natural
inbreeding. (B482.3.w3)
- In captivity, the effects of inbreeding may be compounded by
management of breeding to ensure that different founders provide
equal genetic contributions, and by the lack of the reproductive
competition and associated social stimulation which generally occurs
in the wild. (B482.3.w3)
- "Maximum avoidance of inbreeding" can be carried out
by, in each generation, mating the least-related individuals with each
other. For a captive population of about 50-100 individuals, this should
preserve about 50% of the original genetic diversity over 100
generations. (J23.17.w8)
- The population should be expanded to carrying capacity as fast as
possible, while breeding all available animals and ensuring equal family
sizes. (J23.17.w8)
- As well being advantageous to reduce inbreeding, managing for equal
family sizes slows the rate of unintentional domestication which may
occur from greater breeding of less aggressive, easier to handle, more
readily breeding individuals. (J23.17.w8)
- Genetic diversity is greatest when a 1:1 male: female ratio of
breeding individuals is maintained. Where the actual ratio of breeding
animals is far removed from this, e.g. if social criteria require one male with several females, the males
should be rotated to equalise their breeding potential. (J23.17.w8)
- Genetic strategies and demographic management should be coordinated. (J23.17.w8)
- For maximum preservation of genetic diversity over time, generation
time should be maximised, since there is the opportunity for loss of
genetic variation at each generation. (J54.5.w1)
- To minimise loss of genetic diversity in a captive population,
breeding programmes should:
- Involve an adequate number of wild-caught founders. (J54.3.w2)
- For both conservation and reintroduction purposes, the founder population
should be as large as possible with an approximately even sex ratio. (J23.17.w8)
- To maintain 90% of genetic diversity over a period of 200 years, a minimum of 20 effective individuals, and preferably at least
25-30 is generally required. (J54.5.w1)
- If there are 20-30 effective founders, average heterozygosity
will be preserved. To preserve rare alleles from the wild
population, 30-50 effective founders are required. (J23.27.w3)
- If even one effective founder from the wild population enters the
captive population each generation, this can be sufficient to keep
the captive population representative of the wild gene pool. (J23.27.w3)
- Equalise, as much as possible, the genetic contribution of the
founders to the population. (J23.17.w8,
J54.3.w2)
- It is preferable for genetic purposes to maintain an even sex ratio of
animals contributing to each generation, and for all the members of one
generation to contribute equally to the next breeding generation (i.e.
for an equal number of offspring to be produced and used for breeding). This minimises inbreeding and decreases the risk of domestication
which may arise from the individuals which breed most easily in a
captive situation becoming over-represented in the breeding stock. (J23.17.w8)
- Specify matings to minimise inbreeding. (J54.3.w2)
- Ideally, animals who are least related to one another are mated - a
process known as "maximum avoidance of inbreeding." If this is
used in each generation, then with a starting population of 50-100
animals it would be possible to preserve over half of the genetic
diversity of the original population over 100 generations. (J23.17.w8)
- Maximise the effective population size, by manipulating the number of
offspring per parent, and the sex ratio of the population. (J54.3.w2)
- The effective population size is largest when each individual
parent produces the same number of progeny. (J23.27.w3, J407.17.w1)
- Maintain a demographically stable population. (J54.3.w2)
- To maximise genetic diversity: (B115.9.w13)
- The population should be started with an adequate number of
founders (at least 20 effective, i.e. reproducing, founders).
- The population should be expanded to carrying capacity as fast as
possible; this capacity must be larger than the minimum viable
population size.
- The sex ratio should be equalised.
- Family size should be equalised (in each generation, breeding
individuals should produce equal numbers of offspring to contribute
to the next breeding generation).
- Once carrying capacity is reached, the size and growth of the
population should be stabilised, avoiding population size
fluctuations.
- Once carrying capacity is reached, the population should be
managed for longer generation times.
- Inbreeding should always be minimised.
- Always manage for a stable age structure.
(B115.9.w13)
- To properly use a computer-based demographic program, a model
for each species must be developed based on: (P97.1.w34)
- Estimate of the carrying capacity of the captive breeding
groups.
- The need for surplus individuals (for exhibit in non-breeding
institutions, use in research programmes etc.).
- Determined or estimated fecundity and survivorship by age and
sex classes. In particular, for relatively long-lived species,
adequate first-year survivorship and average annual adult
survivorship data are required, in order to determine the
average number of offspring required per parent to maintain a
stable population size.
- It is essential that mortality data are recorded
accurately, for survivorship data and for detection of
detrimental inbreeding effects.
- The known age and sex structure of the existing population.
This is used with survivorship and fertility data to predict the
demographic structure of the population.
- An explicit plan for moving from the current to the desired
stable population must be devised, tested and agreed on. This
should be examined and stochastic models used to predict
possible fluctuations.
- Note: similar modelling and projections can be used to
formulate a strategy for planned reintroduction projects. (P97.1.w34)
- N.B. A deliberate breeding plan can more effectively preserve the
maximum heterozygosity than can random breeding. (P97.1.w34)
- Note: Following the recommendations for breeding which have
been made based on genetic management may
not always be practical or possible, due to considerations such as
behavioural incompatibilities or psychological problems; differences in
disease status between animals; and logistical problems in moving
animals between collections.
- Use of assisted reproductive techniques (see below: Assisted
Reproduction) may be
appropriate in some cases to allow appropriate genetic matching.
However, the applicability of such techniques in non-domestic
animals is very limited.
Use of reproductive technology in maintaining genetic diversity
- Semen collection and cryopreservation can help in the maintenance of
genetic diversity by increasing the number of potential founders
(collecting semen from wild or captive individuals that, for whatever
reason, have not contributed genetically to the captive population, or
are underrepresented genetically in the population), and, via
cryopreservation, extending the reproductive life of those founders and
their closest descendents. (J54.3.w2)
- Collection and preservation of semen from founders does not allow
preservation of genetic material from female founders. However,
collection of semen from male offspring of female founders
(particularly those genetically underrepresented in the population)
does allow some preservation of their genetic material. (J54.3.w2)
- Ideally, F1 offspring should be produced from different pairings
(male A with female B and male C with female D, but also e.g. male A
with female D and male B with female D), to allow separate
management of the genetic contributions from different founder
individuals. (J54.3.w2)
- Since each F1 individual can have inherited only part of the
allelic diversity of each parent, for maximum probability of
representation of all the allelic diversity of the founders, semen
should be collected from several (ideally six to nine) F1 offspring
of given founders. (J54.3.w2)
- In the absence of founders or their F1 descendents, semen should
be collected and stored from individuals with genomes least exposed
to genetic drift and inbreeding, and within these individuals,
particularly from descendents of genetically underrepresented
founders. (J54.3.w2)
- Careful analysis of pedigrees and calculation of inbreeding
coefficients and the relative genetic contribution of each
founder is required. (J54.3.w2)
- For further information on semen collection and cryopreservation
see: Assisted
Reproduction.
Demographic management
Demographic management is an important part of the management of
captive populations, alongside genetic and behavioural management. (J23.17.w9)
- A demographic model needs to consider the required population size,
as indicated by carrying capacity plus any need to provide surplus
individuals for other purposes. (J23.17.w9)
- The demographic part of a management plan should specify the number,
ages and (in part) sexes of individuals to be retained in the breeding
population and will indicate how many progeny need to be produced
within a given time interval, and specify the number and ages of
animals to be bred.
- Exactly which individuals within a given sex and age class
should breed will depend on genetic management.
- Behavioural management will indicate the grouping and movement
of animals (e.g. rotation of males where behavioural grouping
requires uneven sex ratios of breeding groups).
(J23.17.w9)
- Usually, demographic management aims to produce a stationary
(stable) population, with a constant population size and stable age
distribution. (J23.17.w9)
- A stable population is advantageous because it minimises the
risk of demographic disaster due to random fluctuations or
unpredicted developments in population.
- Production and maintenance of a stable population involves
manipulation of potential survivorships (by removing individuals
from the breeding population) and potential fertilities (by limiting
breeding).
- Animals removed from the breeding population would be
available for other uses.
(J23.17.w9)
- Application of demographic models to assist long-term captive
management and possible reintroduction would require: (J23.17.w9)
- Determination of the existing and, if possible, the potential age-
and sex-specific survivorships and fertilities of the population;
calculation of the existing age/sex structure.
- Calculation of near-future changes in the population size and age
structure, subject to the survivorships and fertilities determined
above.
- Determining the finite rates of change and stable age
distribution associated with the determined sets of existing and
potential survivorships and fertilities.
- Determining, as closely as possible (a) the carrying capacity
for the captive population; (b) the number of surplus animals
needed for other purposes (e.g. reintroduction programmes).
- Within the upper limits set by the potential or maximum existing
values of survivorships and fertilities, construction of (computer-aided) the one or more sets of managed survivorships and
fertilities which, by varying amounts of culling (removal of
individuals from the managed population) and/or breeding
restriction, will produce a stationary captive population.
- Determining the sets of stationary age distributions associated
with each of the calculated stationary sets of managed
survivorships and fertilities. The total number of animals in one
or more of these sets should be approximately equal to the desired
carrying capacity for the population.
- With computer-assistance, preparation of a plan for moving from the
existing population to a stationary population which best fits the
carrying capacity and surplus population desired.
- Selecting individual animals for demographic manipulation in
accordance with genetic models.
- N.B. It would also be necessary to consider stochastic (random
or chance) population fluctuations that might occur in the future.
(J23.17.w9)
Hybrids
- Breeding of hybrids should be avoided by not housing closely related
species with one another. Sub-specific hybridisation also should be
avoided. This may be more difficult if subspecies are not readily
identifiable from one another on the basis of external features, and if records
do not accurately indicate the origin of the individuals.
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| Bear Consideration |
Bears in zoos are managed to differing extents depending on the species
and the priorities of the regional zoo associations. For example:-
In Europe (EAZA)
In North America (AZA
- Bear TAG):
-
Tremarctos ornatus - Spectacled bear,
Melursus ursinus - Sloth bear
and
Helarctos malayanus - Sun bear
are managed under
SSPs.
(W642.Jun07.w1)
- The SSP for
Tremarctos ornatus - Spectacled bear
works closely with the European EEP as well as with zoos in range
state countries (Venezuela and Peru). (W642.Jun07.w1)
-
Melursus ursinus - Sloth bear
is highly endangered and the
CBSG has recommended that North American zoos take the lead in
managing these bears in an international studbook. Additionally, the Bear TAG
"will place high priority on initiating efforts to develop an in situ conservation
program". (W642.Jun07.w1)
-
Helarctos malayanus - Sun bear.
New founders are needed for the North American population.
Importation of founders "needs to be done with an active
conservation linkage program in the range country where the
animals will be obtained in order to protect and preserve as much
remaining habitat as possible while at the same time carrying out
intensive field studies on the sun bear itself. This is vitally
important as so very little is known about these animals in the
wild." (W642.Jun07.w1)
-
Ursus maritimus - Polar
bears are managed under a regional studbook, and zoos are
encouraged "to emphasize the importance of the polar bear's
delicately balanced ecosystem in their conservation message."
(W642.Jun07.w1)
- The Bear TAG does not recommend that zoos in North America breed
Ursus americanus - American black bear
(which have a stable population),
Ursus
arctos - Brown bear (which is stable in its large population
groups) or
Ursus
thibetanus - Asiatic black bear (the North American
population "is an unknown, with few animals, many of varying subspecies, and is considered unsuitable to manage for genetic success").
(W642.Jun07.w1)
Genetic considerations
- It is important to consider the genetic background of individual bears
when forming breeding plans, to avoid breeding bears of unknown or mixed
origin (for species with genetically distinct subspecies or
subpopulations).
(J23.35.w3)
- For further information on subspecies and sub-populations see:
- It is important to take care in choosing bears to be paired, to
avoid inbreeding depression, as has been seen for example in
Ursus
arctos - Brown bears in Scandinavian zoos, where inbreeding has
been associated with reduced litter size. (J17.76.w1,
J23.35.w3)
- Further evidence of inbreeding in this zoo population comes from
the occurrence of true albino individuals, consistent with an
autosomal recessive
allele, and
probably associated with inbreeding. (J23.35.w3,
J17.76.w1)
- There is a significant excess of albinos among inbred brown
bears (p<0.005, Fisher's exact test). (J17.76.w1)
Of the 12 albinos, nine have high
inbreeding coefficients (12.5 to 37.5%); for the other three bears, incomplete
breeding data exist. (J23.35.w3)
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| Lagomorph Consideration |
There are few breeding programmes for wild lagomorph species.
Brachylagus idahoensis - Pygmy
rabbit
- In the breeding program for the Columbia Basin (Washington State,
USA)
Brachylagus idahoensis - Pygmy
rabbit population, it has been found that this distinct
population of the pygmy rabbit is genetically distinct from other
populations. It has also shown that over the past 50 years it appears
to have suffered a considerable loss of genetic diversity. (D372)
- Compared with the Idaho pygmy rabbit, the Columbia Basin pygmy
rabbits have shown lower pregnancy rates, fewer litters per breeding
male, fewer litters per breeding female and fewer young produced per
female. There were also behavioural differences: longer times to show
reproductive behaviour (964 versus 124 minutes) and longer periods
chasing, although similar numbers of mountings. Additionally, Idaho
pygmy rabbits continued breeding through May and into early June,
while Columbia Basin pygmy rabbits did not breed successfully after
12th April. (D372)
- Interbreeding Columbia Basin and Idaho rabbits has produced young,
with successful backcrossing to Columbia Basin pygmy rabbits.
Intercross rabbits have shown markedly increased reproductive success
compared with pure Columbia Basin individuals. (D372)
- Genetic management priorities of the Columbia Basin Pygmy Rabbit
Captive Breeding and Genetic Management Plan (2006) included: (D372)
- "Maintain genetic diversity of Columbia Basin pygmy rabbits by matching the
most appropriate Columbia Basin males and females (minimize loss of genetic
diversity)";
- "Produce offspring of pure-bred Columbia Basin pygmy
rabbits";
- "Conduct intercrosses to produce 87.5% Columbia Basin pygmy rabbits";
- "De-emphasize breeding of rabbits with a high relatedness to the Idaho rabbit
Alder;
- "Conduct intercrosses to produce 75% Columbia Basin pygmy rabbits";
- "Create no new F1 intercrosses (Columbia Basin/Idaho intercrosses) and avoid pairings to produce 62.5% Columbia Basin pygmy
rabbits".
(D372 -
The
Columbia Basin Pygmy Rabbit Captive Breeding and Genetic Management Plan
- full text included)
- It has been noted that there are significant challenges for the
captive breeding and recovery of short-lived lagomorphs. Rapid
expansion of the captive population is important to take the Columbia
Basin pygmy rabbit population out of the demographic and genetic
bottleneck, minimise genetic drift, and to enable harvest of the
captive population, i.e. taking of individuals for the reintroduction
programme, without increasing to unacceptable levels the risk of
extinction of the captive population. (J471.11.w1)
Sylvilagus bachmani - Brush rabbit
- In a propagation and reintroduction plan for riparian brush rabbits Sylvilagus bachmani riparius,
each year new founder animals are taken from a population in the South
Delta on the San Joaquin Sacramento rivers' delta, west of Lathrop,
California, USA and kept in large, predator-free propagation pens.
Surviving founders are then repatriated to their original capture
site, as well as rabbits bred in the propagation pens being released.
(D339,
V.w137)
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| Ferret Consideration |
Breeding programmes for
domestic ferrets vary depending on the goal of the programme, such as
particular coat colours, ferret size or shape. (B651.6.w6,
B652.2.w2)
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| Bonobo Consideration |
Captive bonobo populations in
Europe and North America are managed in an EEP and
SSP respectively, with
studbooks maintained and breeding recommendations made, aiming to minimise
inbreeding. (P86.9.w1)
- Captive bonobo breeding programmes avoid inbreeding as much as
possible, but there is still some evidence of inbreeding and inbreeding
depression. A study found higher mortality in infant bonobos which were
inbred (inbreeding coefficient greater than zero) than in infants
which were not inbred (31.25% versus 12.1%; difference not
statistically significant). (P86.9.w1)
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| Associated techniques linked from Wildpro |
|
|
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- Mammalian mating systems show considerable variation from monogamous
to promiscuous. In some species temporary pairs are formed or males and
females come together only for mating; males may mate with one or
several females; females may mate with one or several males. In other
species, pairings are long term or permanent. In many hoofstock species,
dominant males defend a herd of several females.
- Captive animals frequently are not allowed to chose their own mates. Rather, the
choice is made for them on the basis of genetics and/or expediency (available individuals).
While mate choice may not be relevant in many species, it may play a role
in the breeding of some species, with two individuals not forming a pair
and not breeding, despite the studbook keeper's recommendations.
- Care is required when introducing animals to one another and animals
should be introduced to one another gradually. (B438.24.w24)
- An animal being introduced to conspecifics is at a disadvantage
if also being introduced to a new enclosure. If possible, the animal
should be given a chance to familiarise itself with the enclosure, then
to meet its new mate or group through a barrier before the animals have
full access to one another. Periods of contact usually should be brief
initially and increased as it becomes clear that the animals are
behaviourally compatible. (B438.24.w24)
- Consideration should be given to the need, in species which are
normally predominantly solitary, to separate the male and female for
much of the time. This may improve reduce stress from e.g. food
competition, and may improve both breeding and rearing of young. (B105.19.w6)
- It is important to remember that the introduction of unfamiliar
individuals into a social group, resulting in significant alterations in
social interactions, may produce immediate physiological effects which
may interfere with breeding (e.g. abortion at certain stages of
pregnancy in many small mammals if an unfamiliar male is introduced to
the group). (B105.19.w6)
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| Bear Consideration |
Bears are polygamous/promiscuous in the wild.
In zoos, bears which are intended to
breed are commonly maintained either as a pair or in a group with several
females and one male. In
Helarctos malayanus - Sun
bears in Europe, breeding has been more successful when bears were
kept as pairs rather than in groups. (P6.2.w5)
Recommendations (EEP Ursid Husbandry Guidelines) are as follows:
- If a breeding group is to be kept containing several females,
preferably these females should be sisters or mother and female
offspring. (D247.4.w4)
- If female offspring are to be kept with their mother and be bred,
the male needs to be exchanged for an unrelated male before his
daughters become sexually mature. This reflects the natural, wild
situation more closely than does keeping the same male and
introducing unrelated females to one another. (D247.4.w4)
- With
Helarctos malayanus - Sun bear,
female offspring may be kept with their parents for several years. However,
if unrelated females are introduced to one another there may be (a)
aggression, fighting and injuries; (b) reduced reproductive success.
(D247.4.w4)
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| Lagomorph Consideration |
Domestic rabbits
- The doe should be brought to the buck, not the buck brought into the
doe's territory, to avoid fighting: does tend to be more
territorial than bucks. (B339.8.w8,
B550.16.w16,
J35.151.w2)
- Usually, copulation occurs within a few minutes. (B550.16.w16)
- If a receptive doe does not allow copulation, the doe should be
placed with a different buck; it has been observed that a doe may
reject one buck and accept another buck. (B550.16.w16,
J35.151.w2)
Wild lagomorphs
- With
Romerolagus diazi - Volcano rabbit
at Jersey Zoo, it was found that housing a pair in a small cage was
not successful. Breeding was achieved by development of a 4 x 4 m
area, dividable into two sections each with a tunnel system connecting
underground nestboxes. Male and female would be given one side of the
area each, for a week, then the partition was removed and the pair
left together for 35 days (allowing re-isolation of the female before
the earliest possible littering date , given a gestation of 38 - 40
days. (J51.19.w1)
-
Brachylagus idahoensis - Pygmy
rabbit can be maintained with a female and two males in large pens (e.g. 75 - 100 m²)
(J332.87.w1,
V.w134).
When kept in smaller pens, only a single adult can be kept per pen.
For breeding, a door between the male's and the female's pen is
opened; this can then be left open for two or three days to allow
mating. Animals are not given access to each other in this manner
until the male is known to be in breeding condition (testes are fully
descended, purple and firm). (J332.87.w1)
- Following parturition, either the male (or another male) is
given access to the female again while the young are in the natal
tunnel, or the male is introduced after the young have been
removed from the pen. (J332.87.w1)
- Note: Higher reproductive success appear to occur if
immediate post partum mating is allowed, rather than
waiting and mating the female again later. (V.w134)
- Breeding has been more successful for rabbits kept in a larger,
semi-naturalistic pen rather than in small individual pens. (V.w134)
|
| Ferret Consideration |
- Normally either the female and male are placed together in neutral
territory or the female is placed into the male's territory for
mating. (B651.6.w6)
- The male soon bite's the female's neck and drags her around before
mating. Mating is violent and noisy, with the female screaming.
Afterwrads, both male and female clean themselves, and they may eat a
little. If left together, mating thn starts again. They may be left
together for up to 24 hours. Leaving them longer is not advised as
repeated mating can result in excessive damage to the female's neck. (B651.6.w6)
Once mating is completed, the female's neck should be examined and the
wounds cleaned and treated with antiseptic powder. (B651.6.w6)
|
| Bonobo Consideration |
- In the wild, it is the females that move between
communities, and the status of males may be affected by the
presence of their mother. Therefore in zoo breeding programmes,
generally females rather than males are moved between collections (D386.2.1.w2a,
D386.3.2.w3b,
D386.App1.w6)
- An adolescent female preferably should be transferred into a
group containing an older, established female with whom she can
bond, as occurs in the wild. (D386.3.2.w3b)
- If males must be transferred, it is suggested that transfer occurs
when they are older juveniles or young adolescents, 5 - 7 years of age,
and that they be transferred into a group with other bonobos of the same
age, with whom they can play. (D386.3.2.w3b)
- Males which are genetically overrepresented or genetically
undesirable may be housed in an all-male group. (D386.App1.w6)
|
| Associated techniques linked from Wildpro |
|
Monitoring
Reproductive Health and Reproductive Status in the Female
|
| Many factors may
influence reproductive function, including gross nutritional status,
micronutrients, behavioural and social factors, season etc.
Assessment of reproductive status is required for day-to-day management
of captive breeding programmes, including decision-making regarding animal
housing and pairing; selection of individuals for intensive breeding
management; evaluating the outcome of breeding attempts; group/herd
management; monitoring the health of the fetus and predicting birth dates
to allow preparations for birth; regulation of fertility; and establishing
the causes of breeding failure and monitoring treatment. Monitoring the
timing of ovulation further allows the scheduling of timed matings, and
the application of reproductive technologies such as artificial
insemination, and embryo recovery and transfer. (B445.w4)
A variety of
methods have been developed to monitor the reproductive status and
reproductive health of animals.
Behavioural observation
- An important part of reproductive monitoring is behavioural monitoring.
(B445.w4, J23.38.w2)
- This is non-invasive and does not require any animal contact or
restraint. (B445.w4)
Ultrasonography
- The use of real-time ultrasound examination is of increasing use for
monitoring reproductive health and reproductive status. (B429.38.w38,
B445.w4, P17.60.w1)
- This method allows the organs to be observed without the need for
any surgical invasion. (B429.38.w38,
B445.w4, P17.60.w1)
- The main advantages of ultrasonography are that it is non-invasive
and atraumatic;
gives real-time, visual, reproducible information about the organs;
gives cross-sectional images of the tissues/organs, including images
of organs which are moving; allows organs or other objects to be
measured; can be integrated easily with other methods of examination;
and can be stored. (B445.w6,
P17.60.w1)
- The main disadvantage is the need for physical restraint and often for
sedation or anaesthesia. (B429.38.w38,
B445.w4, B445.w6)
- Note: Some animals can be trained to allow
ultrasonography without either physical restraint or sedation. (V.w5)
- Other potential problems include the need for a good acoustic
coupling with the animal, which may be disrupted for example by fur;
insufficient penetration of sound waves through tissues; the need for
modification of some components to allow for different species; and the
need to develop experience with different species, as well as cost
issues. (B445.w6,
P17.60.w1)
- Ultrasound can be used for sex determination of monomorphic species (species
in which male and female cannot be distinguished by external
characteristics). (B429.38.w38,
B445.w6, P17.60.w1)
- Ultrasound can be used to monitor the female reproductive cycle, but
this involves repeated examination, and physical or chemical restraint
may be needed on each occasion. (B445.w6)
- Use of ultrasonography may allow a diagnosis (e.g. of pregnancy)
from a single observation. (B429.38.w38,
B445.w6)
- Ultrasonography may allow monitoring of early pregnancy and, by
measuring fetal structures and comparing these to reference data, may
allow calculation of the expected parturition date. (B445.w6)
- Ultrasound is able to detect pathological changes in the genital
tract, and may detect pathological changes in other
maternal organs that may affect general health and reproductive
function. (B445.w6)
- Ultrasound may detect abnormalities in the embryo, and sometimes in
the fetus up to as late as the end of the second trimester. (B445.w6)
Vaginal smear
- Vaginal smears can provide useful information about the reproductive
cycle in the female animal. (B445.w4)
- This is a non-invasive technique but requires capture and restraint
of the animal. (B445.w4)
- Some animals can be trained to allow collection of vaginal smears
without either physical restraint or sedation. (V.w5)
Endocrinology (measurement of hormone concentrations)
- Analysis of hormones in the blood, urine, faeces or saliva can be a
precise way of indirectly monitoring reproductive function. However,
before these can be used for monitoring it is necessary to develop a
knowledge of the reproductive physiology of the species, including
hormone metabolism and patterns of hormone secretion and excretion. (B429.38.w38,
B445.w4, B445.w5,
J372.42.w1)
- Hormones may be detected and their concentrations measured using
radioimmunoassays or enzyme immunoassays. (B429.38.w38)
- With the right tests it is possible to monitor the ovarian cycle,
and to detect and monitor pregnancy. (B445.w5)
- Analysis of blood may provide the most information, but generally
requires collection of serial blood samples, which is a practical
disadvantage. (B429.38.w38)
- Non-invasive monitoring of reproductive status may be carried our by
tests on voided urine or faeces. These may allow study of gonadal function
including cyclicity, seasonality, and pregnancy, as well as adrenal (i.e.
stress) status. (B445.w4,
J23.38.w2)
- Detection of excreted hormone metabolites in urine has been
carried out for some years; measurement of metabolites in faeces
was developed later. (B445.w5)
- For each species, it is necessary to determine the main hormone
metabolites produced and the main route of excretion of hormone
metabolites; some species, such as many ungulates, excrete oestrogens mainly in
the urine, while others, such as carnivores (Carnivora - Carnivores (Order)), excrete oestrogens
mainly in the faeces. (B445.w5,
J372.42.w1)
- It is important to validate tests used in each species;
measurements of metabolites which give excellent information on
reproductive status in one species may not be useful in another
species. (B445.w5)
- Urinalysis is advantageous compared with analysis of
blood,
since collection of urine is a non-invasive process. There are
practical problems associated with urine collection, and correction
factors, usually relating values to creatinine concentrations, may
be needed to allow for differences in concentration and volume. (B429.38.w38)
- In equids (Equidae - Horses (Family)), pregnancy can be confirmed by detection of the
pregnancy-specific equine chorionic gonadotrophin in urine. (B429.38.w38)
- Analysis of faeces can be used since fecal excretion is the
predominant route of hormone excretion in many species. (B429.38.w38)
- It is necessary to determine,
for each species, which metabolites should be assayed. (B429.38.w38,
B445.w5)
- Analysis of oestrogens in faeces has been used reliably for
indication of pregnancy in some ungulates and primates. (J372.42.w1)
- Collection of faeces may be easier than collection of urine,
particularly for free-living animals but also for some captive
animals. (B429.38.w38,
B445.w5)
- Complex, laborious laboratory
techniques are required to process the faeces before the assays
can be carried out. (B429.38.w38,
B445.w5)
- For analysis of progesterone metabolites in faeces,
group-specific antibodies against 5-alpha-pregnanes or
5-beta-pregnanes are recommended. (J372.42.w1)
- Saliva contains minute quantities of hormones, which can be measured
by sensitive assays. In most situations, use of this method is limited
by practical considerations regarding collection of saliva. (B429.38.w38)
Laparoscopy/laparotomy
Both laparotomy and laparoscopy may be used to examine the female
reproductive organs and determine reproductive status. (B429.38.w38,
J23.18.w3)
- Both methods are surgical, invasive procedures and require
anaesthesia. (B429.38.w3,
J23.18.w38)
- Laparoscopy causes less surgical trauma than does laparotomy and is
now generally preferred. (B429.38.w38,
J23.18.w3)
- Laparoscopy can be valuable for visualising the internal reproductive
organs and monitoring reproductive cycles in a variety of species. (B429.38.w3,
J23.18.w3,
P1.1976.w1)
- Laparoscopy can be particularly valuable for determining the precise
timing of ovulation, for identifying abnormalities and pathological
conditions of the internal reproductive tract, and in some cases for
surgical treatment of pathology (e.g. adhesions). (B429.38.w3,
J23.18.w3)
Post mortem examination
- As part of the necropsy, the ovaries, uterus and other parts of the
reproductive tract should be examined.
- Thorough examination of the reproductive tract at necropsy allows
correlation with, and confirmation of, findings from ante-mortem
examinations such as ultrasonography. (P6.4.w3)
|
| Bear Consideration |
The reproductive health and
reproductive status of bears have been monitored by a variety of methods
including behavioural observation, physical examination, laparoscopic
examination, ultrasonography and measurement of hormones in blood or
faeces. In bears, it is not possible
to distinguish between failure to conceive and failure to implant. Either
condition could lead to no cubs being born.
Behavioural observation
- Oestrous behaviour, such as presenting to the male and standing to
be mounted by the male, and the occurrence of matings, can be
observed. (J27.65.w1,
J296.66.w1)
Ultrasonography
- Transrectal ultrasonography can be used to assess the reproductive system in
female bears and to confirm pregnancy. (J296.66.w1,
J370.51.w1,
P1.1997.w7)
- Special adaptors, 15, 25 and 50 cm long, allowed scanning of the
elongate genital tract in
Ursus arctos - Brown bear,
Tremarctos ornatus - Spectacled bear
and
Melursus ursinus - Sloth bear,
using a 7.5 MHz curved linear intraoperative transducer and a
real-time B-mode ultrasound scanning system. It was found possible to
examine the urinary bladder, urethra, kidneys (but not the ureters),
vagina, cervix, uterus and ovaries, to detect pregnancy and to detect
abnormalities such as a leiomyoma and purulent vaginitis. (J370.51.w1,
P1.1997.w7)
- There are no differences in the uterus detectable by ultrasonography
between non-pregnant bears and pregnant bears pre-implantation.
Ovulation can be confirmed by the presence of active
corpora
lutea.
Pregnancy can be detected only following implantation of the
embryo. The pregnant uterus shows local uterine enlargement, anechoic
fetal fluid and
endometrial proliferation at sites of implantation.
The placentae appear as hypoechoic discoid structures. (J370.51.w1,
P1.1997.w7)
- Transabdominal (transcutaneous) ultrasonography may be used for
detection of pregnancy in bears, but not for visualisation of the
ovaries, non-gravid uterus or early pregnancy. (J370.51.w1,
P1.1997.w7)
Endocrinology
Blood steroid analysis
- Levels of progesterone in blood can be determined using an
enzyme-immunoassay (EIA) (J370.51.w1
P1.1997.w7)
or radioimmuneassay (RIA). (J27.62.w2,
J206.68.w1,
J371.65.w1,
J372.53.w1)
- A study of
Ursus arctos - Brown bear
found very low concentrations of plasma progesterone (less than
0.1 ng/mL) during February to April (non-breeding season) and
higher levels, indicating active
corpora
lutea, both in
September-October (before implantation) (3.3 +/- 0.9 ng/mL) and in
November-December (after implantation) (3.1 +/- 0.1 ng/mL). (J370.51.w1)
- A study of
Ursus americanus - American black
bears
found that non-pregnant bears, whether in lactational
anoestrus or
non-lactational anoestrus, had very low levels of plasma progesterone
(0.6 - 2.5 ng/mL). Levels were increased in pregnant bears to 5.0 -
12.5 ng/mL during the mid- to late preimplantation period, and at
about the time of implantation in late November/early December
increased a further two- to three-fold. It was noted that both
non-pregnant and pregnant levels of plasma progesterone showed
variation between individual bears and that levels during pregnancy
varied between years for a given bear. (J206.68.w1)
- A study of captive and free-living
Ursus americanus - American black
bears found that serum progesterone levels rose, from a
very low level, about one month after
oestrus, and increased
dramatically around the time of implantation in November/December.
(J372.53.w1)
- A study of Japanese black bears Ursus thibetanus japonicus
(Ursus thibetanus - Asiatic black bear)
found that serum progesterone levels (measured by radioimmuneassay)
were low in April to July, tending to increase in August, rising
much higher November and December then falling to low levels by
March. In captive females known to be pregnant (cubs produced the
following spring), there was a gradual increased from 0.5-2.4 ng/mL
in August to 0.9-3.6 ng/mL in October and reaching significantly
higher maximum levels (7.2-18.0 ng/mL) in December. Serum levels
of estradiol-17β were low in November and December, higher in
January and variable in April to October. For eight pregnant
females, estradiol-17β was high in May (95.6-191.4 pg/mL,
varied in August to October (35.6-143.3 pg/mL), dropped to
significantly lower minimum levels (5.3-11.9 pg/mL) in December,
then increased to 67.6-153.1 pg/mL in January. (J27.62.w2)
- A study of Japanese black bears Ursus thibetanus japonicus
(Ursus thibetanus - Asiatic black bear)
found that serum progesterone levels (measured by radioimmuneassay)
were low in non-pregnant bears, while both pregnant and
pseudo-pregnant bears showed a significant increase in
progesterone in December (time of implantation of the embryo in
pregnant females). Progesterone is produced by the corpora lutea,
not the placenta, in carnivores. (J371.65.w1)
- A study of Ursus thibetanus formosanus in Taiwan, found
that in a female which became pregnant, serum progesterone was 3 ng/mlL in April, lower (about 1.5 to less
than 1 ng/mL) in May to August, rising to about 7 ng/mL in
September. (J467.5.w1)
Fecal steroid analysis
- Analysis of faecal steroid levels may allow non-invasive monitoring
of the reproductive status. (J370.51.w1)
- Levels of progesterone in faeces can be determined using an
enzyme-immunoassay (EIA). (J370.51.w1)
- Fecal progesterone concentrations can be used to monitor luteal
activity in
Ursus arctos - Brown bear:
(J296.66.w1)
- A study of
Ursus arctos - Brown bear
(Ursus arctos yesoensis, Hokkaido brown bears) found that
mean fecal estradiol-17β concentrations were high during the
oestrus period then decreased, while fecal progesterone
concentrations increased after the oestrus period. (J27.65.w1)
- A study of
Ursus arctos - Brown bear
found very low concentrations of fecal progesterone (9.6 +/- 6.7 ng/g
faeces) during February to April (non-breeding season) and higher
levels (50 - 800 ng/g) in bears with active corpora lutea: both
in September-October (before implantation) (151 +/- 133 ng/g) and in
November-December (after implantation) (379 +/- 238 ng/g); in the
first two pregnant bears examined, an increased excretion of
progesterone was recorded. (J370.51.w1)
- In one
Ursus arctos - Brown bear,
fecal progesterone concentrations were found to be very low (0.98
+/1 2.04 ng/g faeces) prior to the mating period, and tended to be
higher (mean 7.36 +/- 7.94 ng/g) in the post mating period, with a
dramatic increase (4,650 ng/g) in December, at the time of embryo
implantation (implantation was confirmed by subsequent
ultrasonographic examination). (J296.66.w1)
- A study of
Helarctos malayanus - Sun bear
found that the level of 17-oxo-androgen in faeces (epiandrosterone
antibody) generally peaked at the time of behavioural oestrus (no such
peak was detected at the time of behavioural oestrus in one bear on
one occasion). Levels of 20alpha-OH-pregnanes (pregnanediol antibody)
increased during the luteal phase of the cycle. The length of the
luteal phase was similar in pregnant and non-pregnant bears. (P6.2.w5)
- The Australasian Husbandry Manual for the Malayan Sun Bear indicates
that measurement of progesterone metabolites in faeces, using an
ELISA,
is useful for monitoring pregnancy in
Helarctos malayanus - Sun bear,
while measurement of pregnanediol-glucuronide is not useful in
this species. It was noted that there were wide variations in
excretion of progesterone over the course of pregnancy and that it was
important to run controls, including a non-pregnant control, in each
assay. (D255.6.w6)
- In a
Tremarctos ornatus - Spectacled bear,
low concentrations of progesterone were measured in faeces, except for
alternating high and low concentrations during the second half of
pregnancy. (J296.66.w1)
- A study of Ursus thibetanus formosanus in Taiwan, found
that in a non-pregnant female, fecal progesterone remained low
(below 25 ng/g faeces) except for two higher readings in late May
and in early August. A female which became pregnant showed rising
fecal progesterone during October (parturition in early November);
fecal progesterone levels also rose in a "pseudopregnant"
female. (J467.5.w1)
Urinary steroid analysis
- Enzyme immunoassays (EIA) can be used to detect total oestrogens,
progesterone, pregnanediol and epiandrosterone. However, these do not
appear to be useful for monitoring reproduction in bears. (J296.66.w1)
- In an
Ursus arctos - Brown bear,
urinary oestrogen concentrations fluctuated at about 0.5 ng/mL;
there was an increase to 3.3 ng/mL in June, but this occurred
after matings, which were observed 27 May to 4 June. Measurement
of urinary pregnanediol and progesterone did not reveal increased
luteal activity. (J296.66.w1)
- In a
Tremarctos ornatus - Spectacled bear,
urinary oestrogen concentrations fluctuated (0.1 to 0.8 ng/mL
urine), with no peak related to observed mating dates. Urinary
progesterone concentrations were generally below 1.0 ng/mL, with
two higher values measured in July and around the time of
implantation, with an increase to 3 ng/mL about three weeks
post-implantation, and a decrease seven days before parturition. (J296.66.w1)
Laparoscopy
- Laparoscopy has been used for monitoring ovarian function in bears.
(B429.38.w38,
J23.18.w3)
Post mortem examination
- Thorough examination of the reproductive tract at necropsy allows
correlation with, and confirmation of, findings from ante-mortem
examinations such as ultrasonography. (J370.51.w1)
|
| Lagomorph Consideration |
- Reproductive health in the rabbit doe is linked to body condition.
The highest energy requirement occurs at peak lactation, about 21 days
after parturition. At this time the doe is in negative energy balance,
mobilising body resources to support lactation. If energy intake is
then inadequate, the doe suffers a decline in body condition,
resulting in decreased reproduction; for good conception rates it is
important that the doe should be in positive energy balance at the
time of mating. Conversely, if the doe becomes too fat then kit
mortality at birth increases. (B614.14.w14)
- Vitamin A balance is important in reproduction. Both excess and
deficiency can result in reduced conception rates, increased fetal
resorption, abortion, reduced neonatal survival and hydrocephalus. (B614.14.w14)
- Diseases which may cause infertility include: (B618.21.w1)
- Abortions and premature births may be seen with: (B618.21.w1)
Behavioural observation
- Experienced personnel may detect when a female rabbit is receptive
by her general behaviour, such as increased restlessness. (J35.151.w2)
- Increased restlessness, trying to reach rabbits in nearby hutches,
and scent marking by rubbing the chin on surfaces are signs of sexual
receptivity. (B550.16.w16)
- A receptive female should allow the male to mount her. However, even
when the female is receptive, mating may not occur immediately when a
male and female rabbit are placed together. (B618.21.w1)
- If receptive, the female will lie down and raise her hindquarters to
allow the male to mate. (B550.16.w16)
Physical Examination
Receptivity
- Receptivity in
Oryctolagus cuniculus domesticus - Domestic
rabbits can be detected by the colour of the vulva - swollen,
moist and
dark red to
purple at the right time for mating, rather than narrow and pale pink. (B612.8.w8,
B618.21.w1,
B550.16.w16)
- However, some females with a purple vulva are not receptive, and
some females have a purple vulva while pseudopregnant or pregnant.
(J35.151.w2)
Pregnancy detection
- In
Oryctolagus cuniculus domesticus - Domestic
rabbits, pregnancy may be detected by gentle palpation of the caudal
abdomen at 10 - 14 days after mating. (B618.7.w7);
12 to 14
days of gestation. (B550.16.w16,
B612.8.w8)
- Fetuses are felt as "marbles" slipping between the
thumb and fingers. (B550.16.w16)
- This is not always effective when only one or two fetuses are
present. (J35.151.w2)
- There is a risk of damaging the fetuses if too much pressure is
used. (B550.16.w16,
J35.151.w2)
- Distinguishing between pregnancy and digesta is more difficult
after the 14th day. (B550.16.w16)
- Note: "Rabbits are particularly prone to fetal loss at day
13, when placentation changes from yolk sacs to hemochorial, and
at 23 days when the fetuses are susceptible to dislodgement by
rough handling." (B612.8.w8)
- By day 24, the mammary glands are notably thicker than in a
non-pregnant doe, if the two are compared directly. (B550.16.w16)
- Examination and palpation can be used to determine mammary gland
development and estimate the number of fetuses in anaesthetised hares. (J148.67.w1)
- In wild
Lepus europaeus - Brown
hares examined under general anaesthesia, it was noted that
palpation did not allow detection of pregnancy before 24 days of
gestation: prior to this it was not possible to distinguish between
fetuses and ingesta. (J148.68.w1)
Ultrasonography
Radiography
- Radiography can be used for detection of uterine enlargement and for
detection of near-term fetuses.
Endocrinology
Blood steroid analysis
- Plasma progesterone and 17B-estradiol can be assayed using
radioimmunoassay (J35.151.w2,
J206.92.w1)
or enzyme
immuonassay (EIA). (J35.151.w2,
J372.X2008.w1)
-
These have been used in
Lepus europaeus - Brown hare.
(J206.92.w1,
J372.X2008.w1)
- In domestic rabbits, measuring plasma or serum progesterone
taken two hours after the ovulatory stimulus can be used to
confirm ovulation (progesterone concentration peaks about 10 hours
before ovulation, then declines sharply). (J35.151.w2)
- In domestic rabbits, the Ocuckeck ELISA kit (Cambridge Life
Sciences) can be used to measure rabbit progesterone and reliably
distinguishes between pregnant and pseudopregnant rabbits at about
day 17 - 18 following insemination; if the doe is not pregnant,
day 18 is an optimal time for repeat mating.
J35.151.w2
- In wild
Lepus europaeus - Brown
hares, serum progesterone levels were measured and correlated
with pregnancy detection by ultrasonography. Mean serum progesterone
concentrations were 97.9 ng/mL in pregnant hares and 14.5 ng/mL in
non-pregnant hares. (J503.35.w4)
- In Lepus europaeus syriacus (Lepus europaeus - Brown
hares) stimulated to ovulate by injection of human chorionic
gonadotrophin, and artificially inseminated, plasma progesterone
levels rose in pregnant hares (from a baseline of < 1.0 ng/mL)
starting on day 2 - 3 and reached a high of 41.4 ng/mL at about day
14, after which levels remained at about this level for a further
week, then increased again rapidly in the fourth week to a peak of
67.7 ng/mL about day 28, followed by a decline to a mean of 37.5 ng/mL
about a week before parturition, another peak of 55 ng/mL a few days
before parturition, then falling, although still relatively high at
37.5 ng/mL 24 hours before parturition, with a rapid fall to baseline
by the day after parturition. In pseudopregnant hares, progesterone
levels also rose from day 2, peaking at days 11 - 18, before declining
rapidly back to baseline at about day 22. (J206.54.w2)
- In
Lepus europaeus -
Brown hares, LH was low (basal) during pregnancy, but in
females left with a male, peaked (31.24 +/- 15.41 ng/mL) on the day of
prepartum mating, 1 - 3 days before parturition, when circulating
progesterone was at about 60 mg/mL. An acute rise in progesterone also
occurred on the day of prepartum mating, reaching 142 +/- 15 ng/mL.
FSH were high at the start and end of pregnancy, increasing rapidly to
peak at day 5, remaining high to day 16, then decreasing, with a significant
rise on the same day as the LH peak, then remaining hgh for three days
before declining around the time of parturition. (J206.92.w1)
Endoscopy
- Vaginoscopy is useful in the diagnosis of diseases of the caudal
reproductive tract. (J513.7.w2)
- Laparoscopy can be used for assessment of the female reproductive
organs in situ, although the ovaries may be obscured by fat. (B602.36.w36,
P6.3.w1)
- See:
Imaging in Lagomorph Diagnosis and Treatment
- Endoscopy
Post mortem examination
- A wide variety of uterine pathologies, as well as the presence or
absence of fetuses either within or outside the uterus, can be
detected at necropsy. (B600.17.w17,
J72.49.w4)
- Examination of the reproductive tract at necropsy can be used to
investigate aspects of female reproduction on a population level in
wild populations. This necessitates the use of dead females, either
killed for other purposes (e.g. hunting) or for the purpose of the
study. (J148.67.w1,
J148.68.w1)
- Note: recently, methods applicable to live hares (e.g.
ultrasonography) have been developed). (J148.68.w1)
- In wild
Lepus europaeus - Brown
hares, placental scars have been used as an indicator of
previous pregnancy. (J503.35.w3,
J503.35.w5) In
one study, in 21 hares more than five years old (as determined by eye
lens weight) in which there were no signs of pregnancies, pathological
alterations of the genital tract were detected. (J503.35.w3)
|
| Ferret Consideration |
The female ferret (jill)
comes into oestrus in the spring (seasonal breeder). While in oestrus, the
vulva is swollen to about the size of a hazelnut. The jill remains in
season until mated or until the end of the breeding season. If unmated,
the vulval swelling may decrease after several weeks but this does not
mean the female has come out of oestrus. Prolonged oestrus causes
Hyperoestrogenism in Ferrets,
with resultant anaemia.
(W755.Sept11.w1)
- Except during the breeding season, the vulva is a simple slit just
ventral to the anus. (B602.1.w1)
- During the breeding season the vulva swells and protrudes (B602.1.w1)
as much as 2-3 cm. Full swelling takes about two weeks to develop and the
jill should not be mated until this time. The female also develops a
vaginal discharge. (B651.6.w6)
- After the jill has been mated, the vulva becomes dry and reduces in
size, and she moults. (B652.7.w7)
- Parturition should occur after 41-42 days. (B602.5.w5)
Monitoring of Reproductive condition
- The onset of oestrus can be detected by examination of vaginal
smears. A cotton-tipped applicator is moistened with sterile saline
and inserted into the vagina; the sample is then rolled across the
surface of a clean glass slide, air-dried and stained with
Wright's stain. (P1.1977.w2)
- Cells for cytological evaluation can be obtained by gently inserting
a 1 mL syringe or plastic pipette 1.0 -1.5 cm into the vagina
until slight resistance is felt, then flushing in 0.05 - 0.1 mL
sterile physiological saline and aspirating it out again, several
times. The contents of the syringe are then expelled onto a clean
slide, sprayed with cytological fixative, air-dried and stained with
Papanicoulaou stain or Wright's stain. During anoestrus, most vaginal
epithelial cells are intermediate or superficial intermediate cells,
with a few parabasal cells; superficial cells are basophilic or
acidophilic with Papanicolaou stain, rarely orangeophilic (which
indicats keratinisation). During oestrus, usually more than 90% of
cells are superficial cells. In the first 3-5 days of estrus,
superficial cells show mixed staining properties (basophilic,
acidophilic or orangeophilic with degenerated nuclei and by 4-6 days,
cells are highly keratinised and mainly anucleate. Neutrophils may be
present at any stage of the cycle. Bacteria are rarely present and are
found in association with superficial cells. If oestrus is prolonged,
numerous bacteria may be present together with neutrophils, cellular
debris and erythrocytes. During proestrus (lasting 2-3 weeks) the size
of the vulva increases. (J212.4.w4)
- After mating, a vaginal smear can be examined to confirm the
presence of sperm. (P1.1977.w2)
Detection of pregnancy
The fetuses can be detected by gentle palpation by about 14 days after
mating. (B631.17.w17,
B602.1.w1); by 21
days. (B652.7.w7)
Pregnancy can be diagnosed using ultrasonography from about 14 days. (B631.17.w17,
B602.1.w1)
- Ultrasonography assists with determining gestational age, number of
fetuses and viability of fetuses, as well as confirming pregnancy. (B631.27.w27)
In the last days of pregnancy the teats become visibly enlarged. (B631.17.w17)
Inducing Parturition
- Litters of only one or two kits may not produce sufficient hormonal
stimulus to initiate parturition. Prolonged pregnancy (43 days) may
result in oversized kits and therefore dystocia, and if parturition
does not occur by this date the kits may die in utero. If
palpation indicates only one kit, induce parturition at 41 days by
giving 0. 5 mg prostaglandin F2α, then 1-4 hours later
6 USP units of oxytocin. Expect parturition 2-12 hours later. If the
jill does not deliver the kit(s) within 24 hours, repeat the treatment
of perform a Caesarean section. (B602.5.w5)
|
| Bonobo Consideration |
Observation
The sexual swellings of female bonobos should be observed and the state
of the swelling recorded, as well as the occurence of menstuation.
- A regular pattern of penineal swelling is generally taken as an
indicator of normal ovarian function.
- If the pattern of swelling is altered or even absent, this may
indicate:
- Pregnancy.
- Ovarian neoplasia
- Ovarian failure
- Altered pituitary function leading to reduced stimulation of the
ovaries to produce the normal hormones (oestrogen and
progesterone).
- Old age.
- Lack of both swelling and menstruation for a long period, in a
female which is not raising an infant, probably indicates a
pathological condition
- Prolonged swelling with erratic reductions in swelling probably
indicates infertile cycles; these may be seen in adolescents and
lactating females, also in females reaching a post-reproductive phase.
- Intra-menstrual intervals with little or no pre-swollen or
post-swollen phase suggests pathology and may be associated with
a pre-menopausal stage.
(D386.2.3.w2c)
Detection of ovulation and
pregnancy using human urinary test kits
- Bonobos can be trained to urinate in response to a cue (P129.1.w5), or
can be kept in an overhead chute (between living areas), with a wire
floor, until they urinate. The urine can then be collected from the
floor using a syringe. This allows collection of urine from a specific
bonobo. (J54.30.w1)
- Human ovulation test kits can be used to detect ovulation and
pregnancy in bonobos. The kit OvuQuick One Step Ovulation,
Nanorepro AG, Marburg, GE, which is based on qualitative detection
of luteinising hormone (LH) in urine was used to monitor ovulation
in bononbos at Milwaukee Zoo, Wisconsin, USA. (J54.30.w1)
- Human pregnancy test kits can be used to confirm pregnancy in
bonobos. At Milwaukee Zoo, Wisconsin, USA, Accustrip hCG Pregnancy
Test (JANT Pharmacal Corporation, Encino, California, USA) was used;
the test is based on qualitative detection of human chorionic
gonodaotropin (hCG). The test was carried out if a female did not show
menstrual bleeding at the expected time. (J54.30.w1)
Monitoring pregnancy using ultrasonography
- Ultrasonography can be used to monitor the progression of pregnancy
in bonobos. With appropriate positive reinforcement training, bonobos
can be scanned without either physical or chemical restraint. this
allows repeated scans and monitoring of the fetus during the whole
gestation. (J54.30.w1,
P129.1.w2)
See Mammal Handling & Movement (Mammal Husbandry and Management)
- Ultrasonography allowed monitoring of fetal heart rate, body
movements and swallowing, and thereby of fetal well-being. (J54.30.w1)
- The examinations allowed size and position to be monitored
for the fetal heart, lungs, kidneys, urinary bladder, gastric
vesicle, limbs, umbilical cord insertion, features of the
face, and the cerebellum.
- Measurements of the size of the embryonic vesicle and the
embryonic crown-rump length were recorded during the first
trimester, with head circumference, biparietal diameter,
abdominal circumference and femur length measured during the
second and third trimesters. These measurements allowed the
construction of fetal growth curves. (J54.30.w1)
- The formation of the placenta and a qualitative assessment
of the amniotic fluid were possible also. (J54.30.w1)
Radiography
- Radiography with positive contrast medium introduced via the cervix
has been used in investigation of infertility. (J339.47.w1)
Laparoscopy
- Laparoscopy has been used to visualise the internal reproductive
organs in the investigation of infertility. (J339.47.w1)
Biopsy
- Endometrial biopsy has been used in investigation of infertility. (J339.47.w1)
|
| Associated techniques linked from Wildpro |
|
Monitoring
Reproductive Health in the Male
|
|
Failure of reproduction may be associated with male infertility. Evaluating
the male for reproductive health is as important as examining the female.
Behavioural observation
- An important part of reproductive monitoring is behavioural
monitoring. (J23.38.w2)
- Males housed in bare (non-enriched) environments may fail to show
breeding behaviour; provision of a more complex environment may improve
breeding behaviour. (B429.39.w39)
History
- Information should be gathered on the animal's age; any previous
disease or injury; whether the individual has previously been fertile
(produced pregnancies and offspring); an estimate of libido; and whether
the animal has been exposed to any pesticides, heavy metals or other
potential toxins. Additionally, consider the captive environment and how
well close relatives have reproduced. (B429.39.w39)
- It is important to remember that the effect of an
"insult" to the testes may take several weeks to become
apparent, due to the length of the spermatogenic cycle. (B429.39.w39)
Physical examination
- The genitalia should be examined in detail. Note the size, tonicity
and integrity of each testis. Note whether there are any adhesions
within the scrotum (indicated by the testes not being normally mobile
within the scrotal sac). Observe and palpate the penis and sheath; check
for any persistent frenulum, phimosis (abnormal contraction of the
sheath) or adhesion preventing proper protrusion of the penis (and
therefore preventing vaginal penetration), as well as for abnormalities
such as penile fibropapillomas. (B429.39.w39)
- Cryptorchidism (undescended testes) is highly heritable, therefore males which are
unilateral cryptorchids (i.e. one testis has descended) and fertile should not be used for
breeding. (B429.39.w39)
- Persistent frenulum and congenital (rather than traumatic) phimosis
are generally genetic in origin, therefore males with these conditions
should not be used for breeding. (B429.39.w39)
- The accessory glands may be assessed by palpation per rectum; chronic
inflammatory conditions of the accessory glands often reduce fertility. (B429.39.w39)
- Note: The state of the testes (e.g. size, tonicity) must be assessed in
relation to season in seasonally-breeding species. (B429.39.w39)
Ultrasonography
- The use of real-time ultrasound examination is of increasing use for
monitoring reproductive health and reproductive status. (B429.38.w38,
B445.w4, P6.4.w6)
- This method allows the organs to be observed without the need for
any surgical invasion. (B429.38.w38,
B445.w4, P6.4.w6)
- The main advantages of ultrasonography are that it is non-invasive;
gives real-time, visual, reproducible information about the organs;
gives cross-sectional images of the tissues/organs, including images
of organs which are moving; allows organs or other objects to be
measured; can be integrated easily with other methods of examination;
and can be stored. (B445.w6,
P6.4.w6)
- The main disadvantage is the need for physical restraint and often for
sedation or anaesthesia. (B429.38.w38,
B445.w4, B445.w6)
- Other potential problems include the need for a good acoustic
coupling with the animal, which may be disrupted for example by fur;
insufficient penetration of sound waves through tissues; the need for
modification of some components to allow for different species and the
need to develop experience with different species, as well as cost
issues. (B445.w6)
- Ultrasonography can be used for sex determination of monomorphic species. (B429.38.w38,
B445.w6)
- Ultrasound is able to detect pathological changes in the genitalia,
such as calcification, fibrosis, cysts or tumours in the testes, and also may allow
detection of pathological changes in other organs, which may affect
general health and reproductive function. (B445.w6,
P6.4.w6)
Endocrinology
- This is less used in assessing male reproductive function than in
assessing female reproductive function. (B429.39.w39)
- Levels of hormones may be assessed in blood, or concentrations of
hormone metabolites in excreta (urine, faeces) may be measured. (B429.39.w39)
- Generally, serial samples are required, with little data being gained
from a single sample. (B429.39.w39)
- Serum testosterone levels may be assayed to confirm puberty (sexual
maturity), and to indicate problems such as deficiency in pituitary
gonadotrophins, and profound Leydig cell dysfunction. (B429.39.w39)
- Testosterone levels show marked seasonal variations in many species,
and also diurnal variation, therefore samples which are to be compared
with one another should be taken at about the same time of day.
- There may be marked variations in testosterone level between species.
- Abnormally low testosterone levels are associated with low libido and
with infertility.
- Very high testosterone levels may be seen in association with an
interstitial cell tumour.
(B429.39.w39)
- The response of the male to an injection of GnRH (gonadotropin-releasing
hormone) can be tested: 25-100
µg GnRH is injected intravenously or intramuscularly, and samples are
collected at 15-30 minute intervals from before injection to two or
three hours after injection. GnRH should stimulate release of LH (luteinizing
hormone) from
the pituitary and result in a detectable rise in serum testosterone
within 15 to 90 minutes; failure of this response indicates an
abnormality in the pituitary or Leydig cells. (B429.39.w39)
- Increased LH in response to GnRH can also be detected; failure of
such increase indicates pituitary dysfunction. (B429.39.w39)
- Interpretation of baseline LH, rather than response to stimulation, is
complicated by the pulsatile release of this hormone, so that even
relatively frequent sampling such as every 15 minutes may fail to
detect an LH pulse, and by possible interference with FSH
(follicle-stimulating hormone)/LH patterns by
anaesthesia. (B429.39.w39)
- Measurement of oestrogen levels in blood or urine may indicate the
presence of Sertoli cell tumours or seminomas, although not all Sertoli
cell tumours secrete oestrogen. (B429.39.w39)
- High levels of stress hormones (glucocorticoids) may be associated
with the presence of large numbers of pleomorphic (various-shaped) sperm. (B429.39.w39)
Semen evaluation
Collection of semen for examination
- Semen for evaluation generally is collected by electroejaculation
carried out on an anaesthetised individual. (B429.39.w39)
- Electroejaculation requires the animal to be in a surgical plane
of anaesthesia. The anaesthetised animal is placed in a position
allowing access to the anus and the glans penis. Copper or stainless
steel electrodes are arranged longitudinally, or less commonly as
rings, on a plastic or Teflon rectal probe with a diameter about the
same as that of a normal fecal bolus. Longitudinal electrodes may be
arranged on one side of the probe only, to provide stimulation
ventrally, towards the accessory glands. The ejaculate should be
collected into a pre-warmed (to prevent cold-shock) sterile plastic
vial. (B429.39.w39)
- Stimuli, either direct current or alternating current, are applied
generally in groups and with increasing voltage, generally starting
at 2.0 to 5.0 volts and rarely exceeding 10 volts. (B429.39.w39)
- An ejaculate containing sperm is generally produced in response to
electrical stimulation. (B429.39.w39)
- Contamination with urine may occur; this is more common with the
use of some sedatives including xylazine,
diazepam and acepromazine,
all of which relax the urethral musculature. (B429.39.w39)
- Electroejaculation using a rectal probe is safe when used
correctly; males show normal sexual behaviour and may mate and
fertilise females within days of electroejaculation. (B429.39.w39)
- Individuals of some species have been trained to allow semen
collection into an artificial vagina (various species), or by manual
stimulation of the penis (some canids (Canidae - Dogs, foxes (Family))). (B429.39.w39)
- It is possible to collect mature spermatozoa post mortem, by flushing
the ductus deferentia and caudal epididymes with warmed saline
or air. If there is a delay in collection, the tissues should be
maintained at 5 °C prior to collection. (B429.39.w39)
Evaluation
- The volume, colour and pH of the ejaculate should be tested
immediately. A yellow colour indicates urine contamination; this also
will lower (in carnivores) or raise (in ungulates) the pH. (B429.39.w39)
- Other common evaluations are for sperm concentration (this can be
greatly reduced with urine contamination), percentage motile sperm and
forward motility, both assessed at 37°C, percentage abnormal sperm,
with records of types of abnormalities (e.g. abnormal head shape or
size, missing midpiece, coiled flagellum, biflagellate, bicephalic or a
defective acrosome). (B429.39.w39)
- For samples with very high sperm concentrations (greater than one
billion sperm per millilitre) it is necessary to dilute the semen
(in saline or an appropriate culture medium) before motility can be
evaluated. (B429.39.w39)
- Motility estimates should be repeated for several hours at
intervals of 30 to 60 minutes, since infertility has been reported
associated with rapid loss of motility. (B429.39.w39)
- Reduced longevity in vitro is common with samples which are
urine contaminated; seminal fluid constituents also can reduce
motility. (B429.39.w39)
- More complex evaluations of sperm viability can be carried out,
such as the ability of sperm cells to move through cervical mucus
(assessed using a polyacrylamide gel) and sperm penetration assays
looking at penetration of heterologous ova. (B429.39.w39)
- Examinations should be made on several (three to four) ejaculates
collected at intervals of three to four weeks before a judgment is made
on the male being infertile. (B429.39.w39)
Testicular biopsy
- Biopsies can be used to assess the presence of cellular elements
within the testis, the presence or absence of sperm production, and the
severity of degeneration of the testis in acquired diseases. (B429.39.w39)
- Anaesthetise the animal. Surgically prepare the scrotum. Stabilise the
testis within the scrotum. Using an ultrafine surgical blade, make an
incision through the scrotum, tunica vaginalis and tunica albuginea, and
though into the testis to a depth of 2 - 3 mm. Using moderate pressure at
the neck of the scrotum, press the surface of the testis though the
incision. Shave the testicular sample off the testis with a sharp
scalpel. Place the sample in glutaraldehyde (not formalin; formalin
distorts chromatin patterns and the walls of the seminiferous tubules).
Suture all layers of the biopsy site. Give prophylactic systemic
antibiotics. (B429.39.w39)
- Alternatively a needle biopsy may be taken but this often does not
provide sufficient tissue for histological evaluation. (B429.39.w39)
|
| Bear Consideration |
The size and weight of the
sexual organs in bears varies with body size. The size of the testes of
Ursus arctos - Brown bear,
Helarctos malayanus - Sun bear
and
Melursus ursinus - Sloth bear
were found to be similar to one another, but the size of the accessory
glands was related to body size. (P9.2004.w5)
-
Ursus arctos - Brown bear
(200 - 250 kg bodyweight); testis diameter 26.1 +/- 7.1 mm (breeding
season, n=4); 17.9 +/- 2.2 mm (non-breeding season, n=2).
-
Helarctos malayanus - Sun bear
(70 - 85 kg bodyweight) testis diameter 24.5 +/-3.8 mm (breeding season,
n=4); this species is a non-seasonal breeder.
-
Melursus ursinus - Sloth bear
(74 - 156 kg bodyweight) no breeding season data; testis diameter 17.8
+/- 8.4 mm (non-breeding season, n=4).
-
Tremarctos ornatus - Spectacled bear
(150 - 160 kg bodyweight; testis diameter 26.6 +/1 3.1 mm (breeding
season, n=8); 25.7 +/- 2.1 (non-breeding season, n=3).
(P9.2004.w5)
Physical examination
- The presence of the testes can be confirmed, and their size
measured, in anaesthetised males. It may also be possible to detect
abnormalities such as the presence of a tumour. (J296.55.w1,
P6.4.w3)
Ultrasonography
- Ultrasonography can be used to assess the reproductive system in
male bears. The testes can be scanned and measured transcutaneously,
while the internal organs can be scanned transrectally. The size of
the testes and accessory glands can be determined and abnormalities
(e.g. tumours, fibrosis, calcifications) detected. Ultrasonographic
examination allows detection of abnormalities in the male reproductive
tract before they can be detected by physical examination and before
any apparent effect on sperm quality. (P6.4.w3)
- In a study, a B-mode ultrasound scanning system was used, with a
10 MHz linear array for transcutaneous imaging of the testes and a
7.5 MHz curved linear transducer fitted into a specially designed
adapter used transrectally for imaging internal structures such as
the urinary bladder, urethra, prostate gland and ampulla.
Testis, prostate and ampulla volume were calculated from
measurements of their length, width and height.
Abnormalities such as testicular fibrosis, a tumour in the testis
of one
Tremarctos ornatus - Spectacled bear
and a hyperechoic structure in the ampulla were detected. (P6.4.w3)
Endocrinology
- A study of
Ursus americanus - American black
bears found that serum prolactin, measured with a
radioimmuneassay, varied seasonally, being lowest in December (1.1 +/-
0.1 ng/mL (mean +/- SD), and highest in May (17.6 +/- 4.7 ng/mL),
preceding the June testosterone peak. Prolactin concentrations were
considered to be a useful indicator of testicular steroidogenic
activity. (P1.1993.w3)
Electroejaculation
- Electroejaculation can be used to assess semen characteristics such
as ejaculate volume, sperm concentration, total sperm count, sperm
motility, viability and abnormal morphology. (J296.55.w1,
P6.4.w3)
Post mortem examination
- Thorough examination of the reproductive tract at necropsy allows
correlation with, and confirmation of, findings from ante-mortem
examinations such as ultrasonography. (P6.4.w3)
|
| Lagomorph Consideration |
Infertility in the male may be congenital (can occur in a significant
proportion of domestic rabbit bucks). or associated with infectious
diseases:
(B618.21.w1)
Physical examination
- The genitalia can be assessed by physical examination. In males older than about 10 - 12 weeks, the testes should be
seen in the scrotal sacs on either side just cranial to the penis;
they should be symmetrical, smooth and non-painful. (B601.2.w2)
- The position (intra- or extra-abdominal) of the testes can be
determined during examination of live wild hares; this can be useful
in assessing the timing of the breeding season. (J148.67.w1)
- Testicular swelling may indicate: (B601.App2.w20)
Ultrasonography
- Ultrasound can be used for assessing the reproductive tract in
male lagomorphs. (J503.35.w1,
J503.X.w1)
- In wild
Lepus europaeus - Brown hare,
a 7.5 MHz transducer was used rectally to image the pelvic portions
of the male genital tract. (J503.35.w1)
- The contents of the scrotum of 28 New Zealand white rabbits was
evaluated using a 5 MHz linear array transducer, with the rabbits
in dorsal recumbency. For the examination, a rubber pad, 0.8 cm
thick and with a central hole 0.5 cm diameter was placed between
the testis and the rabbit's body, ultrasound coupling gel was
applied to the scrotum, and a rubber sac containing 250-300 mL tap
water was placed over the scrotum as a stand-off. (J503.X.w1)
- The dimensions of the testes were measured (right testis
average 3.2 +/- 0.08 cm (mean +/- SEM) long, 1.1 +/- 0.03 cm
wide; left testis mean 3.3 +/- 0.09 cm long, 1.1 +/- 0.03 cm
wide). (J503.X.w1)
- The testicular parenchyma was described as "homogenous
and moderately echoic" while the cauda of the
epididymis seen in sagittal plane images was "a
homogenous, less echoic structure localised next to the
testicular parenchyma" and the caput epididymis was
"smaller than the cauda, homogenous and less echoic
compared with the testicular parenchyma" but could
only be visualised in eight rabbits (28.6%). (J503.X.w1)
- Abnormalities which could be detected included biopsy needle
scars (hyperechoic, from 3-4 days to day 14 after biopsy),
while in a testis undergoing necrosis, reduction in testicular
volume and variation in echogenicity were noted. (J503.X.w1)
Electroejaculation
- Semen can be collected from rabbits and hares by electroejaculation.
(J372.93.w1,
J372.X2008.w1)
- In wild
Lepus europaeus - Brown hare,
semen samples were collected by electroejaculation using specially
designed equipment. (J503.35.w1)
Endocrinology
Semen evaluation
- Average ejaculate volume in a medium-sized domestic rabbit is 0.8 mL.
(B550.16.w16)
- Samples can be assessed by light microscopy. (J372.93.w1)
- The concentration of sperm can be assessed in a Thom-Zeiss chamber,
using the cytometric method. (J372.93.w1)
- Staining using a Live/Dead Sperm Viability Kit (L-7011, Molecular
Probes) can be used to assess the percentage of live sperm. (J372.93.w1)
- In wild
Lepus europaeus - Brown hare
semen samples were evaluated for volume, colour, concentration of
sperm, sperm motility and sperm morphology. (J503.35.w1)
- Note: there is variation is semen composition between
individuals, also in an individual there are variations such as cyclic
changes in sperm count. (B550.16.w16)
Post mortem examination
- The position (intra- or extra-abdominal) of the testes can be
determined; testicular mass can also be measured. These can be
useful in assessing the timing of the breeding season. (J148.67.w1)
- Histological examination of testicular parenchyma can be used to
assess seasonal regression and reactivation of testes. (J503.35.w2)
- Orchitis and Epididymitis in Rabbits
may be detected at necropsy. (B600.17.w17,
J72.49.w4)
|
| Ferret Consideration |
-
On the male, the preputial opening is easily seen on the ventral surface
of the abdomen, caudal to the umbilicus, and the os penis can be
palpated. (B602.1.w1)
- Outside the breeding season the male's testes are small and
intra-abdominal. In early spring, they enlarge and descend into the
scrotum. (B651.6.w6)
- Enlargement and descent of the testes starts once day length increases.
As testosterone production increases, the hob puts on weight and the
activity of the skin glands increases, with a resultant increase in odour
as well as stickiness of the fur coat. (B631.17.w17)
- Spermatogenesis starts in December and continues to July. (B602.1.w1)
- Electroejaculation with a rectal electrode can be used in an
anaesthetised ferret to obtain a sperm sample. The semen is mixed with
an extender then can be examined for sperm concentration and mobility
(and can be used for artificial insemination or cryopreserved for
later use). (J206.86.w1,
P1.1977.w2)
- Anaesthesia with medetomidine or xylazine plus ketamine is less
likely to rasult in urine contamination than diazepam,
acepromazine or inhalational anaesthetics.
- Semen needs to be collected into a warm collection vessel (glass
or plastic) to avoid cold shock of the sperm.
- Three series of stimulations can be given, totalling 80
stimulations, In each, the voltage is increased from zero to the
maximum required voltage over a period of a second, held for 2-3
seconds then stopped, with a three second break between
stimulations and a 2-3 minute rest between sets of stimulations.
Suggested:
- Series one: ten stimulations at 4V, ten at 5V, ten at 6V;
- Series two: ten stimulations at 5V, ten at 6V, ten at 7V;
- Series three: ten stimulations at 6V, ten at 7V.
- Usually 0.05 +/- 0.01 mL semen can be collected by this method,
with about 706 x 106 spermatozoa/mL, with 67% normal sperm and 80%
motility. (B232.17.w17)
|
| Bonobo Consideration |
- The external genitalia of primates should be examined as part of a full physical
examination e.g. when individuals are moved between collections. (B10.44.w44f)
- Male bonobos can be trained to allow masturbation and semen
collection by keepers; collected semen can be used for artificial
insemination [as well as for evaluation of male fertility]. (P129.1.w5)
|
| Associated techniques linked from
Wildpro |
|
|
|
| Assisted
reproduction includes "any technique that circumvents natural
procreation to produce young." The most commonly used assisted breeding techniques are artificial
insemination and embryo transfer. (J23.38.w2)
Note:
- Assisted reproduction can be a part of conservation, but is not
sufficient in itself for conservation. (J3.143.w10,
J370.57.w3)
Assisted reproduction should only be used as part of an overall
breeding programme, to counteract the effects of human interference
which may make breeding difficult. (P1.1976.w1)
While assisted breeding has been responsible for some landmarks in
breeding of wild carnivores, these techniques are only a very small part of
conservation. (J370.57.w2)
- Assisted reproduction techniques have only limited
applicability for use in non-domestic species. Techniques developed for
assisted reproduction of humans and domestic animals cannot easily be
applied to other species; much needs to be known about the reproductive
physiology of the species before even the simplest techniques, such as
artificial insemination, can be used successfully. (B23.61.w19,
J23.38.w2, J370.57.w3)
- Effective use of assisted reproductive technologies requires
considerable research for each species: to characterise normal sperm
traits and develop methods for cryopreserving and thawing sperm; to
characterise the reproductive cyclicity of the female and understand
the timing of ovulation;
to understand seasonal aspects of reproduction; to learn the in vivo and in vitro
requirements of gametes;
to characterize ovulation timing, oestrus
synchronization, induction of ovulation, and maturation of oocytes; to
develop appropriate in vitro sperm-oocyte interaction and
culture conditions for gametes and embryos; to find the appropriate
site for deposition of sperm or embryos in the female; and to
understand the effect of stress on reproduction. (J23.38.w2)
Benefits of assisted reproductive techniques
In non-domestic animals, reproductive technologies including assisted
reproduction and germ plasm banks may be useful to:
- Improve fertility. (B445.w4)
- Stimulate reproduction in individuals which are genetically
important and increase founder representation in small populations. (B23.61.w19,
B445.w4)
- Allow production of offspring while the male and female are kept
at different locations, reducing the need for shipping individual animals between collections, with associated reduction in risks,
permits and expense. (B23.61.w19,
J3.143.w10, J23.38.w2,
J51.18.w1, P1.1976.w1)
- This also removes the possibility that, after the transfer has
taken place, the two animals turn out not to be a compatible pair. (J23.38.w2,
P1.1976.w1)
- Reduce the risk of transfer of microparasites and macroparasites
(which may be transferred between locations with their host). (B23.61.w19,
J51.18.w1,
P1.1976.w1)
- Allow insemination when a pair of animals are behaviourally incompatible, or there is a risk to the female during normal mating.
(B23.61.w19, J51.18.w1)
- Introduce new genetic material into captive populations, either from other
captive populations or from the wild. (B23.61.w19,
B445.w4,
J51.18.w1,
P1.1976.w1)
- This could reduce the need to bring new wild animals into
captivity to maintain the genetic diversity of the captive
animals. (B23.61.w19,
J23.38.w2)
- Introduce new genetic material into isolated wild populations,
either from other isolated wild populations or from captive
animals (i.e. genetic transfer between in situ populations or
from ex situ to in situ populations). (B23.61.w19,
B445.w4,
J23.38.w2)
- Allow preservation of genetic material (frozen semen) for future
use, including from individuals in (presently) healthy wild
populations (i.e. develop genome resource banks), preserving genetic
diversity and providing insurance against genetic loss, disease and
unnatural selection.
(B445.w4, J51.18.w1,J23.38.w2)
- Possibly improve bloodlines, reducing or eliminating undesirable
genetic traits. (P1.1976.w1)
- Allow breeding of individuals which are behaviourally unsuitable for
mating, (B445.w4) for example due to
imprinting. Note: it is preferable to avoid imprinting or development of other behavioural impediments to normal mating.
- Allow breeding despite anatomical problems, (B445.w4)
e.g. when a male is fertile but has suffered a penile injury reducing his ability to mate
naturally, or if a genetically valuable female has an injury such as a broken
pelvis making normal parturition impossible.
- Increase population growth. (B445.w4)
Artificial insemination
Artificial insemination is the assisted reproduction technique most
likely to be of practical use for wildlife propagation. (J23.38.w2)
- Artificial
insemination involves collection of semen from the male and deposition of
the semen into the female. The semen may or may not be stored before use,
either short term (days, in a proper medium) or longer term (frozen). (J23.38.w2)
- In domestic mammals, artificial insemination is commonly used in farm
species, particularly cattle, for convenience (the farmer does not have to
maintain a bull), to improve desired characteristics (by using semen from
a bull proven for such characteristics) and to allow a given bull to sire
greater numbers of offspring.
- Collection of semen from most mammal species requires
electroejaculation of the male, under deep anaesthesia. A rectal probe
of an appropriate size and shape for the species is used, with either
AC or DC power. Semen collected is evaluated microscopically as well
as macroscopically. Semen can be used for immediate insemination, or
placed in an appropriate extender and held for up to two to three days
at 5°C, or frozen for storage (equilibrated at 5°C, pelleted on dry
ice then deposited in liquid nitrogen). It may be possible to use
frozen semen successfully after several years of correct storage. (P1.1976.w1)
- Note: Collection of semen from conscious mammals by
electroejaculation is painful. (J296.64.w1)
- Sperm from different species, and even from different individuals
within the same species, may show different susceptibilities to freezing
and thawing, i.e. different percentages of sperm which are mobile and able
to fertilise an egg following freezing and thawing. (B445.w8)
- In non-domestic mammals, deposition of sperm into the female
requires an anaesthetic, which has deleterious effects on sperm
transport. Fertility is much higher if laparoscopic intrauterine
deposition is used rather than intravaginal deposition. (B23.61.w19)
- Note: While artificial insemination may have an important role to play in breeding programmes for some endangered species, it should be seen only as one tool in such a
programme, not as an end in itself.
(J51.18.w1, P1.1976.w1)
- Note: In some countries there may be legislation restricting
the use of electroejaculation for semen collection to licensed
veterinarians.
Oocyte collection (gamete rescue)
- Oocytes can be "rescued" from the ovaries at necropsy or
at the time of ovariohysterectomy. Generally, immature eggs are
collected from the ovary and matured in vitro. This technology
has been proved by use in domestic cats (oocyte retrieval, maturation,
fertilisation, embryo transfer and subsequent birth of live young).
Immature eggs from a variety of wild felids have been collected and
matured in vitro. (B23.61.w19)
In vitro fertilisation
- This has been used primarily in felids. (B23.61.w19)
- Development of ovarian follicles is stimulated by injecting equine
chorionic gonadotrophin (eCG) or using follicle-stimulating hormone (FSH)
followed by human chorionic gonadotrophin (hCG). (B23.61.w19)
- Oocytes can be collected by transabdominal laparoscopy; this is
comparatively easy in felids but more difficult in some other taxa
(e.g. in mustelids (Mustelidae - Weasels (Family))
the ovaries are embedded in adipose tissue and in
canids (Canidae - Dogs, foxes (Family))
they are enclosed in a bursa, therefore it is not possible to observe
ovarian activity or retrieve oocytes). (B23.61.w19)
- Collected oocytes are examined by stereomicroscopy and oocyte-cumulus
cell complexes classified as mature (with loose and expanded oophorus
cells) are co-cultured with sperm for about 20 hours then assessed for
fertilisation and embryo cleavage at about 30 hours post insemination.
- Confirmed embryos can be transferred into an appropriate female. (B23.61.w19)
Embryo transfer
-
Embryo transfer
involves the collection of fertilised ova or embryos from one female and
deposition into the uterus of another female. Either fresh or frozen
embryos may be used. (J23.38.w2)
- Embryo transfer has been highly developed for use in domestic cattle, to
increase reproduction from highly desirable cows. It has been used in non-domestic animals, but its use is likely to remain minor.
|
| Bear Consideration |
Wildlife Information Network again thanks
WSPA for its invaluable sponsorship without which
the Wildpro "Bears: Health and Management" volume would not have been researched and published. A message from WSPA follows:
WSPA
does not condone the captive breeding of
bears unless there is a programme to rehabilitate and release the
cubs back to the wild as part of a valid conservation or animal
welfare programme.
WSPA believes that bears should not be kept in captivity in
enclosures (including zoo enclosures) where their living
environment lacks sufficient space and natural habitat to enable
the bears to exhibit their natural behaviour.
|
Artificial Insemination
Artificial insemination could
be used as a means of transferring genetic material between isolated bear
populations in the wild, and between captive collections.
- Electro-ejaculation and collection of semen has been carried out on anaesthetised
Ursus arctos - Brown bear,
Ursus thibetanus - Asiatic black bear
and
Ursus maritimus - Polar bear.
(J27.60.w1,
J27.64.w3,
J27.66.w1,
J296.55.w1,
P1.1974.w1,
P1.1976.w1,
P17.43.w2)
- In
Ursus thibetanus - Asiatic black bear,
sperm concentration, total sperm count and motility were highest,
and contamination with urine, leucocytes and bacteria was
minimised, when the bladder was emptied prior to electrical
stimulation, an increasing rather than constant voltage was used
and the collection took place via a urethral catheter rather than
directly into a test tube. (J296.55.w1)
- Motile sperm have been observed following cryopreservation of
ejaculate from
Ursus arctos - Brown bear
and
Ursus thibetanus - Asiatic black bear,
suggesting that frozen semen might be useful for artificial
insemination in these bears. However, numbers of mobile and/or
progressively motile sperm were reduced in frozen-thawed samples. (J27.64.w3,
J27.66.w1,
P17.43.w2)
Embryo transfer
Embryo transfer could be used as a way to protect existing genetic diversity in bears (J296.51.w1)
and to transfer genetic material between isolated bear populations.
- Bears show seasonal breeding (except for
Helarctos malayanus - Sun bear)
and delayed implantation. These features increase the potential
usefulness of embryo transfer, since transplantation can be carried
out without the donor and recipient having their reproductive cycles
synchronised. (J296.51.w1)
- It has been proven possible to collect a
blastocyst nonsurgically
from an
Ursus americanus - American black bear,
and to laparoscopically transfer the blastocyst to a recipient
Ursus americanus - American black bear,
resulting in the birth of a live, apparently normal cub (the cub,
together with a cub genetically descended from the recipient, died at
several weeks old when the maternal den was flooded). (J296.51.w1)
- Further work is required to improve the technique for passing
the stylet through the cervix, which is tortuous, for embryo
collection and to allow non-surgical implantation into the
recipient. Use of oestradiol cypionate (156 µg/head) has improved
passage of a stylet through the cervix. (J296.51.w1)
Oocyte recovery and maturation
- Oocytes
have been recovered from antral follicles of the excised ovaries of
bears (hunter-killed
Ursus americanus - American black bear,
and euthanased elderly
Helarctos malayanus - Sun bear
and
Melursus ursinus - Sloth bear),
and incubated to produce nuclear maturation (indicated by development
to metaphase II chromosome configuration). Unsurprisingly, efficiency
of recovery of oocytes capable of maturation appeared to be affected
by the age, reproductive status and general health status of the bears
involved. It was noted that considerable research would be required
before "oocyte rescue" could be used for ursid conservation.
(J369.269.w1)
|
| Lagomorph Consideration |
Artificial insemination
-
Artificial insemination can be carried out in rabbits. (B550.16.w16,
B614.2.w2)
-
Artificial insemination has been carried out in hares (Lepus
spp.) and
Sylvilagus
spp. (J206.10.w1,
J296.4.w1)
Semen collection
-
In domestic rabbits, semen can be collected from the buck into an
artificial vagina of appropriate size. (B550.16.w16,
B614.2.w2)
- Note: This is unlikely to be useful for wild lagomorphs.
(J206.43.w1)
-
An artificial vagina for rabbits generally consists of a plastic or
thick-walled rubber casing and a thinner rubber liner. (B550.16.w16)
-
For example, 1.25 inch diameter radiator hose, 5 inches long, lined
with surgical drainage tubing and leading to a 5 mL test tube,
attached to the tubing via a rubber stopper with a hole bored
through), maintained at about 40 °C (not over 45 °C) by use of a
water jacket. (B614.2.w2)
- If the temperature is too low, the buck may not ejaculate; if it
is too warm, the sample may be contaminated by urine. (B550.16.w16,
J35.151.w2)
-
Either a female teaser rabbit is used or a rabbit skin is worn over the
arm of the person collecting the sample and is held such that it is
easy for the buck to mount it. (B614.2.w2,
B550.16.w16,
J35.151.w2)
- A young male can easily be trained to mount a rabbit skin. The
male should be allowed to approach the skin and sniff it when it
is first introduced, not have the skin moved towards the rabbit,
which may be intimidating. Usually the male will soon approach and
mount, ejaculating as soon as the penis has entered the artificial
vagina (held in the operator's hand under the skin). Initially,
during training, the skin should be introduced every day or every
second day. (J35.151.w2)
-
Usually collections are made twice a week. Daily collections have been
made for a year. (B614.2.w2)
-
Semen collected from daily collections contain more (two to four
times) spermatozoa than those from weekly collections, but excessive
collection can cause decreased semen production and decreased sex
drive. (B614.2.w2)
- With semen collection very frequently (two or three times a day
for nine months, seminal fluid was found to contain antibodies to
sperm antigens. (J35.151.w2)
-
There are both breed and individual differences in semen production. (B614.2.w2)
-
In hares (Lepus europaeus - Brown hare),
collection of semen by artificial vagina apparently is not possible. (J372.93.w1)
-
Semen can be collected from
Lepus europaeus - Brown hare
by electroejaculation under anaesthesia. (J372.93.w1,
J372.X2008.w1)
- If no ejaculate was obtained after four or five impulses, the
collection attempt was cancelled. (J372.93.w1)
- An interval of at least one week between collection of samples.
(J372.93.w1)
- Sperm mass has also been collected from lagomorphs post mortem
or at castration, by slicing or cutting the epididymis or the vas
deferens and epididymis in 0.9% physiological saline or another
appropriate diluent. (J346.46.w1,
J369.144.w1,
J495.28.w4)
- Semen has been collected directly from the epididymis of hares (Lepus americanus - Snowshoe hare,
Lepus europaeus - Brown hare)
and
Sylvilagus floridanus - Eastern
cottontail and used successfully for artificial insemination. (J206.10.w1,
J206.54.w1,
J296.4.w1)
Semen dilution and storage
-
Semen can be stored for up to 12 hours undiluted and used for
insemination, or diluted in glucose-yolk-citrate and used within four
day. (B614.2.w2)
-
Successful insemination can be made after diluting the semen up to 10
times in physiological saline or in Ringer's solution or Krebs-Ringer
solution. (B614.2.w2,
J35.151.w2)
- Antibiotic should be added. (J35.151.w2)
-
Semen from rabbits can be stored for longer periods in Tris buffer-based diluents with
glucose and citrate, plus a cryoprotectant for frozen storage,
commonly dimethylsulphoxide (DMSO). (J372.64.w1,
J372.93.w1)
- Semen is diluted in Tris-citrate-glucose-DMSO extender at 33 °C
then cooled to 5 °C over 90 minutes, then cooled in straws (0.25
mL) above liquid nitrogen for 10 minutes then plunged into the
liquid nitrogen. To thaw, straws are thawed in a water bath at 37
°C for 30 seconds. (J372.93.w1)
-
The rates of freezing and thawing can greatly affect the quality of
sperm following thawing. In one study, using semen in Tris-citric-acid-glucose
extender with 1.75M DMSO and 0.05 M sucrose as cryoprotectants,
freezing in liquid nitrogen vapour for ten minutes gave significantly (P < 0.01) higher post-thaw fertility compared with freezing in a
freezer at minus 30 °C. Thawing at 50 °C for 10-12 s produced higher
numbers of young born and numbers of live young than thawing at 70 °C
for 10 - 12 s. (J296.60.w1)
-
Semen from
Lepus europaeus - Brown hare
has been frozen diluted in extender and gave acceptable motility
post-thaw. (J372.93.w1)
- Extender used (rabbit semen extender): Tris 3.028g, citric acid
1.675 g, glucose 1.25 g, dimethylsulphoxide (DMSO) 4.5% v/v, egg
yolk 17% v/v and distilled water to 100 mL). Dilution of
ejaculates of at least 0.4 mL, greater than 75% motile spermatozoa
and sperm concentration over 250 x 106 per mL to give 5
x 106 spermatozoa per 0.25 mL. Post thaw, motility
40.50 +/- 4.21%, live spermatozoa 35.05 +/- 4.21%, percentage with
normal acrosomes 76.10 +/- 3.69%. (J372.93.w1)
Insemination of the female
-
For successful fertilisation, 0.3 - 0.7 mL of sperm suspension,
containing 20 - 50 x 106 spermatozoa should be inseminated
into the female. (B614.2.w2)
- As low as 1 x 106 spermatozoa may produce acceptable
fertility. (B614.2.w2)
- Semen should be examined at least for apparent viability and
motility, before being used. Place a drop on a warmed slide for
microscopic. examination. (J35.151.w2)
- In fertile males, at least 70% of the sperm usually show
progressive forward motility. (J35.151.w2)
- A 15 - 20 cm length of tubing, rubber, soft plastic or glass can be
used, with an external diameter of 6 - 7 mm. (B614.2.w2)
- Inseminate when the doe is in oestrus. (B614.2.w2)
- Receptivity can be determined by the red colouration and
turgidity of the lips
of the vulva (versus white or pale pink vulval lips in
non-receptive does). (J296.68.w1,
J296.66.w3)
- Note: Conception rates with artificial insemination can be similar to
those from natural mating if carried out when the female is receptive.
(B614.2.w2,
J296.66.w3)
- Conception when the female is not receptive to natural
mating results in a lower conception rate. (B614.2.w2,
J296.66.w3)
- Both the colour of the vulva and general behaviour can be used
to determine when the doe is receptive. In general, the vulva of a
receptive doe is purple, rather than pale pink, the the doe may
appear restless. (J35.151.w2)
- Hold the doe on her back and deposit the sperm suspension deep into
the vagina, in the cervical area. (B614.2.w2,
J35.151.w2)
- OR place the doe in a box with a non-slip surface and lift
the tail gently. A receptive doe then shows lordosis, lifting her
hindquarters, while a non-receptive doe fails to lift her
hindquarters, and clamps down her tail. (J35.151.w2)
- Insert the pipette at an angle of 45 degrees. (J35.151.w2)
Stimulation of ovulation
It is necessary to stimulate the doe to induce
ovulation. This can be carried out by:
- Mating by a vasectomised buck (not always effective). (B614.2.w2,
J35.151.w2)
- Several vasectomised bucks must be kept, since some females
will reject some males. (J35.151.w2)
- Note: vasectomised males can develop anti-sperm
antibodies in their seminal plasma, therefore the vasectomised
buck should not be allowed to mate the female until 1 - 4
hours after insemination. (J35.151.w2)
- Mounting and ejaculation by the buck does not always result
in ovulation. (J35.151.w2)
- Injection of the GnRH analogue
buserelin
(Receptal (Intervet Schering-Plough)
- data sheet included)
intramuscularly or subcutaneously. (B600.4.w4,
B601.15.w15,
B603.5.w5,
J35.151.w2,
J296.68.w1)
- This method is simple and reliable, causing ovulation about
10 - 12 hours after injetion. It can be used repeatedly. (J35.151.w2)
- A recent alternative has been addition of a GnRH analogue (buserelin 5 µg or triptorelin 5
µg) to the semen suspension, for mucosal vaginal absorption. (J296.68.w1)
- In
Lepus europaeus - Brown hare,
intramuscular injection with buserelin (0.4 mL Receptal, i.e. 0.00168
mg buserelin) during the breeding season resulted in an increase in
blood progesterone on the fourth day after injection, and successful
pregnancies following artificial insemination with diluted semen (in
Tris buffer extender). (J372.X2008.w1)
- Injection with buserelin outside the breeding season did not
cause an increase in plasma progesterone concentration. (J372.X2008.w1)
- Alternatives which have been used include:
- Injection with human chorionic gonadotropin (hCG). (B550.16.w16,
J35.151.w2)
- Intravenous injection is required. (B550.16.w16,
J35.151.w2)
- 20 - 25 IU in 0.25 mL sterile water. (B550.16.w16)
- This is highly antigenic, therefore with repeated use
antibodies are produced and further use does not cause
ovulation. (J35.151.w2)
- Injection with human chorionic gonadotropin (100 units
intravenously) in Lepus europaeus syriacus
Lepus europaeus
- Brown hare. (J495.28.w4)
- This was effective for successful induction of ovulation
throughout the year. (J495.28.w4)
- Injection of 20 - 25 IU luteinising hormone (LH), intravenously or
intramuscularly. (B614.2.w2,
B550.16.w16)
- Injection with 20 UI of eCG (Folligon,
Intervet) to synchronise
oestrus and induction of ovulation using 10 µg of GnRH (Fertagyl,
Janssen
Animal Health). (J296.66.w3)
- Injection with FSH twice daily for three days then LH at 50
mg/kg on the fourth day in
Sylvilagus floridanus - Eastern
cottontail. (J296.4.w1)
- Note: Feeding of artificially inseminated domestic rabbit
does with sprouted wheat
improved sexual receptivity and litter size. Sprouted wheat contains
high levels of 6-MBOA (6-methoxybenzoxazolinone), a non-oestrogenic
phenol which has been shown to stimulate reproductive functions. (J372.99.w1)
|
| Ferret Consideration |
- Ferrets are photoperiod controlled seasonal breeders. Oestrus occurs
when daylength increases after a period of short daylength - about
three weeks after an abrupt change from eight hours light/16 hours
darkness to 16 hours light/eight hours darkness, under artificial
lighting conditions. Changing the light conditions periodically can be
used to bring the female into oestrus two or three times a year (by
changing lighting hours every four months or every two months,
respectively), and at whatever time of the year is desired. (J503.43.w1)
- Ovulation occurs in response to the physical stimuli of mating:
copulation leads to release of LH (about 3-4 fold elevation) which
leads to ovulation of about 12 oocytes 30-40 hours after copulation.
Fertilisation is most effective up to 12 hours after ovulation,
therefore at 42-52 hours after copulation. (J503.43.w1)
- Treatment with
Human chorionic gonadotropin
(hCG) also induces release of LH and thereby ovulation. (J503.43.w1)
- The optimum dose of hCG for ovulation is 100 IU per ferret. (J54.7.w2)
Artificial Insemination
- Artificial insemination has been used successfully for breeding
ferrets. It is necessary to induce ovulation, e.g. by injection of 100
ug LH prior to insemination. (P1.1977.w2)
- Sperm for insemination can be obtained by electroejaculation. (J206.86.w1,
J206.92.w1,
P1.1977.w2)
- Sperm has also been obtained from the epididymis of surplus male
ferrets immediately following euthanasia. (J54.17.w2,
J422.11.w1)
- Semen can be cryopreserved and used later for fertilisation. (J206.86.w1)
- Inoculation of semen into the jill's vagina does not result
in fertilisation, even if the jill ovulates. (J54.17.w2,
J422.11.w1)
- Artificial insemination can be carried out laparascopically or
surgically to deposit semen into the vagina. (J54.17.w2,
J206.92.w1,
P1.1977.w2)
- Non-surgical artificial insemination is successful if sperm are
deposited transcervically, into the uterine body or anterior horns. (J54.17.w2)
- Improved results were obtained by insemination 24 hours after
injection of hCG, rather than at the same time (79% pregnancies
versus 17%). (J54.17.w2)
- Artificial insemination has been used to improve breeding and
improve founder representation of the endangered
Mustela nigripes - Black-footed ferret
including (via cryopreservation) allowed breeding by males several
years after the death of the ferret. (J503.44.w1)
|
| Bonobo Consideration |
Assisted reproduction may
be required when genetically it is preferred that two animals should
breed, but the two individuals show an inhibition against mating. This may
happen in bonobos which have lived with each other for prolonged periods
and it is possible that this represents a natural barrier to inbreeding. (P1.2002.w10)
Artificial insemination
-
Non-invasive artificial insemination (AI) has been carried out in
bonobos with the help of positive reinforcement training. A female was
trained to provide urine samples (to enable accurate timing of
ovulation) and to permit a speculum to be inserted, allowing
insemination deep into the vagina. Training also permitted collection
of ejaculate from a male. After the artificial insemination, the
female was allowed to mate with males who had been fitted with vas
deferens clips to render them infertile. Two months later the female
tested pregnant (urinary test). The offspring was proven to be the
result of the AI. (P1.2002.w10)
|
| Associated techniques linked from Wildpro |
|
|
|
| Every animal
born within a zoo ought to have a place within the zoo's overall
collection plan. Control of reproduction may be used as one method of
population control in a zoo. Factors which should be considered before the
decision to use any form of contraception is made include possible
negative impacts on behaviour, as well as side-effects which may occur
following use of either surgical or pharmacological contraception methods.
(J23.38.w3, D271,
D273)
Captive breeding programmes for many species have become more efficient
and control of breeding is an integral part of responsible zoo animal
management. (B445.w9)
There are many
circumstances in which it is desirable to prevent or delay reproduction,
including:
- Prevention of overcrowding;
- Avoiding inbreeding when related animals are maintained in the same
enclosure;
- Genetic management, such as reducing breeding of animals which are
already genetically over-represented in a population;
- Avoiding producing hybrids or sub-specific hybrids;
- Preventing hybrid animals from breeding.
- Increase the time between generations.
Various methods may be used for preventing reproduction including: (P76.1990.w1)
Physical separation of males and females. (D271.w2)
This may be appropriate
for:
- Species which are solitary except during the breeding season;
- Social species which may be maintained in all-female and
all-male groups;
- Some social species with a short, well-defined breeding season.
(B429.40.w40)
- Note: Reproductive failure may occur if animals are
prevented from breeding for several years, even when only
separation has been used. (B429.28.w28)
Holding single-sex groups of animals at each collection. (D271.App1.w3)
Surgical castration of males, or ovariectomy
or ovariohysterectomy of females
- These procedures require anaesthesia and a surgical operation.
- These methods are permanent.
- Sexual behaviour is generally eliminated, which may be
advantageous in some situations but may be undesirable in other
situations.
- Social hierarchies may be disrupted.
- Desirable secondary sexual characteristics may be lost (e.g. the
mane in lions), or seasonal cycles disrupted (e.g. deer antlers
remaining in velvet). (B23.40.w18)
- Note: Viable sperm may remain in the vas deferens after
castration; the
male should not be considered sterile immediately (six weeks is
recommended as a conservative estimate). (B23.40.w18)
(B23.40.w18, B429.40.w40,
B445.w9, D271..App1.w3)
Vasectomy in males/tubal ligation in females;
- These methods require anaesthesia and a surgical operation.
- Although theoretically reversible, these operations should be
considered permanent.
- The technique required for reversing vasectomy requires
highly skilled microsurgery and has been developed only for
humans.
- injection of
a sclerosing agent into the cauda epididymis or vas deferens is a possible non-surgical method
in males.
- Hormone production and sexual behaviour typically are
unaffected.
- In females, generally ovariectomy is preferable to tubal
ligation on health
grounds, although in very long-lived species the possibility of
long-term bone density loss due to lack of oestrogen (as in
humans) might make tubal ligation preferable.
(B23.40.w18, B429.40.w40,
P1.1991.w7,
B445.w9, D271.App1.w3)
Occlusion of the vas deferens, either by a material inside the vas
deferens to plug it, or by extravasal devices such as clips. (B23.40.w18,,
B429.40.w40,
B445.w9 P1.1991.w7)
- These procedures require anaesthesia and a surgical operation.
- Theoretically reversible, but in practice should be regarded as
irreversible since preventing sperm
passage without either perforation of the vas or development of
fibrosis is not reliable by any method developed to date. (B23.40.w18,
B429.40.w40)
- Fertility may not be restored after removal of a vas deferens
plug. (P9.1995.w9)
- The animal may develop antisperm antibodies, compromising
subsequent fertility even if the occlusive device is removed and
the vas is patent. (B429.40.w40)
- Note: Viable sperm may remain in the vas deferens; the
male should not be considered sterile immediately (six weeks is
recommended as a conservative estimate). (B23.40.w18)
Use of IUDs
- These may be appropriate for some species, such as the great
apes. (B23.40.w18)
Use of steroid hormones in females - synthetic oestrogen plus synthetic
progestin, or synthetic progestin alone - orally, by intramuscular
injection or in a surgical implant. (B23.40.w18,
B429.40.w40, D271.App1.w3,
P76.1990.w1)
- Commercially available contraceptives include: megestrol acetate
for oral use (Ovaban®, Schering-Plough; Megace®, Bistol-Meyers
Squibb); medroxyprogesterone acetate for oral use (Provera®,
Pfizer Inc.) or intramuscular injection (Depo-Provera®, Pfizer
Inc.); melengesterol acetate in an implant (ZooPharm); and
levonorgesterol implant (Norplant®, Wyeth-Ayerst). (J296.66.w2)
- These must be given at appropriate intervals depending on the
hormone and formulation used: daily (oral drugs); every two to three
months (e.g. Depo-Provera (Upjohn) - medroxyprogesterone acetate
in a slow-release formulation); replaced at intervals of two years
(melenegestrol acetate (MGA) in a silicone matrix); or left for up
to five years (Norplant (levonorgestrel)). (B429.40.w40,
P76.1990.w1)
- Implants must be placed in the animal, which requires an
anaesthetic. (B429.40.w40)
- Implants may be lost, particularly in primates which may
remove them. (B429.40.w40)
- It may be difficult to tell whether an implant is still in
place or has been lost. (B445.w9)
- Loss of implants may be reduced by using implants such as
Norplant, injected through a trochar (the small entry wound
reduces the risk of loss during grooming); by gas
sterilisation then thorough degassing and use of sterile
instruments for implantation; and by separating the implanted
individual from her social group while the implant site heals.
(B23.40.w18)
- With oral contraceptives, it is vital to ensure daily
ingestion, and this can be difficult. (B23.40.w18)
- For seasonal breeders, oral or injectable steroids may be used during the breeding
season only. (P76.1990.w1)
- Note: when a progestin is first given, it may not block ovulation if
follicles are already present, therefore the female should still
be considered fertile for at least the first two weeks. (B23.40.w18)
- If given to animals which are pregnant, there may be adverse
effects on pregnancy (e.g. abortion in golden lion tamarins),
parturition (prevented in contracepted Odocoileus virginianus - White-tailed deer),
or the offspring of the implanted animal. (B429.40.w40)
- If oestrogens are given to a lactating female, lactation may be
suppressed. (B429.40.w40)
- There may be considerable variations in time to ovulation
following removal of implants. (B23.40.w18)
- Prolonged use in felids, canids (Canis lupus
- Wolf) and other carnivores has been associated with
development of a variety of proliferative diseases (including
aggressive tumours) and inflammatory diseases of the reproductive
tract. (B23.40.w18,
P1.1991.w7,
P9.1995.w9)
- Mibolerone (Cheque, Upjohn Co.) is a synthetic androgen used in
domestic female dogs, but may cause increased aggression. (B23.40.w18)
Immunocontraception in males. (B429.40.w40)
- Male animals can be immunised against LH or GnRH.
- Spermatogenesis is blocked.
- This method also interferes with production of testosterone;
typical male behaviour is suppressed, therefore this method is
functionally similar to castration.
(B429.40.w40)
Immunocontraception in females, using porcine zona pellucida (PZP) vaccines. (B23.40.w18,
B429.40.w40,
B445.w9, D271.App1.w3,
J296.66.w2, P1.1991.w7,
P1.1993.w4)
- Commercially-available PZP vaccines include SpayVac® (TerraMar
Environmental Research Ltd.) and a vaccine available from Zoo
Montana. (J296.66.w2)
- The "standard" dose of PZP vaccine is about 65 microgrammes of
antigen (equivalent to about 5000 zonae pellucida)
- In theory, immunocontraception prevents fertilisation without affecting either
ovulation or the expression of oestrous behaviour. In practice there may be wider effects on the ovary, although
these may be reduced by increased purification of the antigen. (P1.1991.w7)
- There may be reactions, sometimes severe, if Freund's adjuvants
are used, while other adjuvants may have a lesser
immunostimulatory effect therefore result in less successful
contraception. (P9.1995.w9)
- Freund's Complete Adjuvant may lead to tuberculosis-positive
test reactions, and produces small abscesses in some animals. (B23.40.w18,
B445.w9,
P1.1993.w4)
- Alternative adjuvants which result in adequate,
contraceptive,
antibody titres include Freund's incomplete adjuvant (FIA =
Quil-A, Superfos Specialty Chemicals, Vedback, Denmark),
Carbopol (Goodrich Co., Cleveland, Ohio, USA) and DEAE-dextran
(Sigma Chemical Co., St Louis, MO, USA). (P1.1993.w4)
- The antigen/adjuvant emulsion has high viscosity, which may
cause problems for delivery by dart, although delivery by this
method can be used. (P1.1993.w4)
- Usually three injections are given, at intervals of about a
month. (B23.40.w18)
- The female should not be considered protected from contraception
until after administration of the last booster vaccination. (B23.40.w18)
- Immunocontraception may last for only 6-12 months, which is
adequate for seasonal breeders with a breeding season of under six
months. (B23.40.w18)
- However, some seasonal breeders, if not pregnant (due
to contraception), may continue to cycle for longer periods
than is usual. (B23.40.w18)
- PZP immunocontraception may fail because: (J54.24.w3)
- The vaccine fails to elicit sufficient antibody titres; this
is most likely to occur due to relative homology between the
PZP and the zona proteins of the target animal; (J54.24.w3)
- The antibodies produced in response to the PZP fail to
cross-react with the sperm receptor proteins on the zona
pellucida of the target animal;
- The antibodies formed do not remain at sufficiently high
levels over the breeding season. (J54.24.w3)
- Long term use of PZP for contraception may be irreversible. (B23.40.w18)
- Note: PZP vaccines should not be given to pregnant females until more data is
available; early abortion and premature births have been recorded
in treated individuals. (B23.40.w18)
Hormone agonists or antagonists in males
- Hormone agonists act by negative feedback. Because pituitary
hormones respond to pulsatile rather than chronic GnRH
stimulation, continuous administration of a GnRH agonist, after an
initial stimulatory phase, causes suppression of production of LH
and FSH.
- In males, suppression of LH and FSH results in suppression of
spermatogenesis.
- These drugs should function as "equivalent to reversible
gonadectomy." (B23.40.w18)
- Because testosterone production is suppressed, typical male
behaviours and secondary sexual characteristics are suppressed.
- In some species, reduced aggression of the male may be
desirable.
- If maintenance of male-typical behaviour and/or
characteristics is desirable, the GnRH agonist may be given
together with testosterone.
- Leuprolide (Leupron, TAP) is a GnRH agonist available in
injectable form which has had some success in males of various
species. (B23.40.w18)
- Use of GnRH agonists may become more applicable if subcutaneous
implants are developed to allow sustained release of the GnRH-analogue
peptide hormones.
- Use of antagonists (which block hormone actions by binding the
bind hormone receptors) would be practical only if they became
sufficiently inexpensive for chronic use.
- Use of the GnRH analogue deslorelin in wild carnivores has had
variable results. (J370.57.w2)
(B23.40.w18, B429.40.w40,
J370.57.w2)
- Commercially available GnRH analogs include deslorelin (Suprelorin®,
Peptech Animal Health), and leuprolide acetate (Lupron Depot®, TAP
Pharmaceuticals; and a formulation from ZooPharm). These are given
intramuscularly. (J296.66.w2)
Antispermatogenics in males - bisdiamine.
- Antispermatogenics inhibit spermatogenesis in a reversible manner and do not
affect hormone levels.
- The main side-effect in humans (inhibition of alcohol
dehydrogenase) is not a problem in animals (since they do not usually
consume alcohol). (P1.1991.w7)
- In wolves (Canis lupus
- Wolf),
a bisdiamine (WIN 18,446, Stirling Winthrop, Rensselaer, New York,
USA) was found to effectively and reversibly block spermatogenesis
in males when given orally at a dose of at least 190 g/kg (in
meat) prior to the beginning of spermatogenesis and continuing
through the breeding season. It was not effective in wolves
treated after the start of the breeding season at a dose of 250
mg/kg. (P9.1995.w8)
- Bisdiamine is commercially available only in a laboratory-grade, very expensive
formulation (Fertilysin, Aldrich). (B23.40.w18)
- Bisdiamine WIN 18,446 is commercially available as Fertilysin®
(SAF Bulk Chemicals, Milwaukee, Illinois, USA). (J296.66.w2)
- Bisdiamine is teratogenic to developing embryos; it is important, during
administration of the drug, to separate
males from females which might be pregnant.
(B23.40.w18)
- Indenopyridine analogues have been successfully used in rodents,
but in cats they caused unacceptable side effects (e.g. lethargy,
occasionally bloody diarrhoea). (B23.40.w18)
- Busulfan suppresses spermatogenesis but also bone marrow,
therefore is unsuitable. (B23.40.w18)
Disadvantages of reproductive control
All methods of reproduction control have disadvantages.
- One obvious potential problem is failure of the chosen method. With
implanted contraceptives, this may be caused by failure of the
contraceptive, or by loss of the implant from the animal. (P76.1990.w1)
- A potential problem when any form of contraception has been used on
a temporary basis is failure of the animal to return to normal
reproductions after the period of contraception. (B23.40.w18,
P76.1990.w1)
This may occur even when the only form of contraception used is
physical separation. (B429.28.w28)
- Effective breeding control may result in an aged population with
reduced fecundity and reduced breeding potential if the population
suffers from a catastrophe such as severe disease. (B429.28.w28)
Reproductive control of free-ranging wild
animals
- There has been considerable research into the possibilities of
contraceptive products useable in free-living wild animals, and in
particular the development of immunocontraceptive vaccines. (P69.22.w1)
- It is probable that the use of wildlife contraceptives will be
limited; they may be useful in urban/suburban areas when traditional
methods such as trapping and hunting cannot be used. (P69.22.w1)
- In general, except with very short-lived species, contraception
would not cause rapid reductions in populations. (P69.22.w1)
- The following criteria would be required for contraception to be
useful for control of pest populations: (P115.1993.w1)
- Existence of appropriate technology to reduce fertility;
- Development of an effective delivery mechanism for wild animals;
- Use of the contraception results in the required goal of reduced
damage due to animals;
- The effects are humane and non-toxic;
- The product being target-specific, cost effective and
environmentally acceptable.
(P115.1993.w1)
- The American
Association of Wildlife Veterinarians has suggested (1993
resolution) the following criteria to be met in order for fertility
control to be an acceptable method of regulating populations of
free-ranging wild animals: (D367)
- "The compound doe not affect the health of target
species and humans.
- A risk assessment is completed delineating potential effects
on nontarget species.
- The application is limited to site-specific, well-defined
subpopulations or populations.
- The application does not alter the gene pool of the species.
- Sort- and long-term effects on population dynamics, including
age structure and behaviorral effects, are evaluated through
modeling and monitoring.
- The program is evaluated by regulatory and wildlife
management agencies before use, with full public participation.
- Costs of the fertility control program are borne by the
organizations or public that benefit from the program."
(D367)
|
| Bear Consideration |
Wildlife Information Network again thanks
WSPA for its invaluable sponsorship without which
the Wildpro "Bears: Health and Management" volume would not have been researched and published. A message from WSPA follows:
WSPA
does not condone the captive breeding of
bears unless there is a programme to rehabilitate and release the
cubs back to the wild as part of a valid conservation or animal
welfare programme.
WSPA believes that bears should not be kept in captivity in
enclosures (including zoo enclosures) where their living
environment lacks sufficient space and natural habitat to enable
the bears to exhibit their natural behaviour.
|
Note: Collections holding animals within a breeding programme
(e.g. EEP animals in Europe) should consult with the species coordinator
and follow their recommendations regarding control of reproduction. (D247.6.w6)
Reproduction in bears may be controlled by a variety of methods, each
with advantages and disadvantages.
- Note: "The limited data available for pubertal animals suggest that
contraception probably does not affect future fertility, but this is not
certain." (D315)
Physical separation
- Separating males and females during the breeding season may be
considered as a method of reproductive control for northern bear
species with a defined breeding season. (D247.6.w6)
- Separation may be required for as long as five months. (D247.6.w6)
- Separated individuals should be kept in enclosures well away from
one another; if they remain within range of olfactory communication this could
act as a stressor and promote
stereotypic
behaviours. (D247.6.w6)
Hormonal contraception
- Hormonal implants have been used in various bear species including
Helarctos malayanus - Sun bear,
Ursus americanus - American black bear,
Melursus ursinus - Sloth bear,
Ursus arctos
- Brown bear and
Ursus maritimus - Polar bear.
(P76.1990.w1)
- Implants of melengestrol acetate (MGA) have been used in bears. (B445.w9)
- Implants containing 500 mg melengestrol are effective for at least
two years. (D247.6.w6)
- The bear has to be immobilised (anaesthetised) and the
implant placed surgically. (D247.6.w6)
- An
Ursus arctos
- Brown bear conceived 87 months after implantation of an
MGA implant. (P1.1991.w)
- Note: After use of an implant, the bear should then be given
at least one season without contraception, to reduce the risk of
adverse health effects. (D247.6.w6)
- Oral contraceptives can be used. (D247.6.w6)
- Note: Care is required to ensure that the dose is
swallowed and has not been spat out. (D247.6.w6)
- In a female
Ursus maritimus - Polar bear
at Cologne Zoo, 400 mg medroxyprogesteronacetate (two pills of
Clinovir 200, Upjohn) were given weekly, crushed and mixed with
honey which was then presented to the bear on the end of a spoon.
(D247.6.w6)
- No side effects were noted with this contraception. (D247.6.w6)
- In a female Kodiak bear (Ursus arctos
- Brown bear), oral megestrol acetate was given at 200 mg
daily (0.25 mg/lb bodyweight) for 64 days, in fish, starting 1st
April - about two weeks before oestrus was expected, and appeared
effective: the female, which had cubbed for the previous seven
years, did not produce cubs. (P1.1978.w1)
- N.B. Long-term progestin treatment of felids (Felidae - Cats (Family))
has been associated with the development of uterine and mammary
pathology, including neoplasia. (J296.66.w2,
D315).
Additionally, progestins may enhance the onset of signs of diabetes
mellitus. Therefore synthetic progestins, with or without
oestrogen, are not recommended for long-term use in carnivores. (D315)
- Progestins should not be used in pregnant females as they may
inhibit uterine contractions and therefore interfere with the normal
progression of parturition. (D315)
- Use of progestins during the period of embryonic diapause could
stimulate the onset of active gestation, resulting in an earlier than
normal birth date. (D315)
- Progestins may or may not interfere with the development of normal
oestrous behaviour. (D315)
Immunocontraception using Porcine Zonae Pellucidae (PZP)
- This involves two vaccinations in the first year, one at one to two
months before the start of the breeding season and the second one to
two weeks before the breeding season. For seasonally breeding species,
a single vaccination is then required yearly, four weeks before the
breeding season. In
Helarctos malayanus - Sun bear,
which does not have a defined breeding season, a booster would be
required every eight months. (D247.6.w6)
- The vaccine can be given by darting (remote injection). However,
until more is known about the effects, it is preferable to immobilise
the bear so that a blood sample can be taken to check antibody titres.
(D247.6.w6)
- The vaccination should not affect the reproductive behaviour of the
bears. (D247.6.w6)
- This has been used in
Ursus arctos
- Brown bear and
Ursus thibetanus - Asiatic black bear.
(No data was available on its efficacy in these species). (P1.1993.w4)
- In
Helarctos malayanus - Sun bear,
two females were treated with PZP. In one, treatment was followed by
absence of ovarian activity; a normal
oestrus cycle occurred four
years after PZP treatment and when the bear died one year after the
end of the endocrine study the ovaries were found to be grossly and
microscopically normal. In the other treated bear, persistent
follicular and luteal activity occurred. However, similar
activity/lack of activity were also seen in other individuals not
treated with PZP. (J296.62.w1,
P6.2.w5)
- PZP contraception has been used in 25 bears with 100% effectiveness
(no pregnancies); boosters are recommended at 12-month intervals. (J54.24.w3)
- More information is required:
- At present this should not be used in bears which may be needed
to reproduce later, since it is not known whether the effects are
reversible. (D247.6.w6)
- At necropsy, ovaries of both treated and untreated bears should
be collected, preserved in 4% formalin (make small incisions to
increase formalin penetration into the tissue) and sent to the
Institute for Zoo Biology and Wildlife Research (IZW), Berlin,
Germany. (D247.6.w6,
D247.7.w7)
See:
Necropsy of Mammals
- Note: use of a PZP vaccine is not recommended in carnivores
since it has been associated with damage, potentially permanent, to
ovarian tissue, which may result in infertility. (D315)
Castration, ovariectomy/ovariohysterectomy and sterilization
(vasectomy/tubal ligation)
- These methods are surgical and require anaesthesia. (D247.6.w6)
- These methods are irreversible. (D247.6.w6)
- Castration affects reproductive behaviour, and castrated males tend
to gain weight. (D247.6.w6)
- Some castrated males continue to show breeding behaviour. (D315)
- Vasectomy is not recommended because vasectomised males are
likely to continue normal sexual behaviour and copulation with
females, which can induce ovulation followed by pseudopregnancy. (D247.6.w6)
During pseudopregnancy, high endogenous progesterone levels develop (J467.5.w1);
repeated exposure to endogenous progesterone not associated
with pregnancy may carry risks similar to those recognised with
repeated exposure to exogenous progestins (see above). (D315)
- Castration or ovariohysterectomy are preferred for permanent
sterilisation. (D315)
Antiprogestin to prevent implantation
- Antiprogestins competitively displace progesterone at the cellular
receptor and thereby prevent implantation or induce abortion. (J296.56.w1,
J370.57.w1,
P1.2002.w2)
- Because bear reproduction involves a period of embryonic diapause
prior to implantation, and progesterone levels increase at the end of
the embryonic diapause, displacement of progesterone using an
antigestagen (AG) has been considered as a means of preventing the
blastocyst from implanting. (P5.39.w9)
In seasonally breeding bears, antiprogestins can be
given parenterally during diapause (October) or in the early
post-implantation period. (P1.2002.w2)
- In an
Ursus arctos - Brown bear,
anti-progestin given two weeks post-implantation successfully
disrupted pregnancy. (J296.66.w1)
- The anti-progestin J956, a norethindrone derivative, given to
bears (several
Ursus arctos
- Brown bear, one
Tremarctos ornatus - Spectacled bear
and one
Ursus
thibetanus - Asiatic black bear) intramuscularly, either alone
at 10 mg/kg or together with an oestrogen (ethinyloestrodiol at 10
µg/kg), in mid-October, prior to implantation, appeared to
prevent pregnancy developing. (J370.57.w1)
- Ten bears (eight
Ursus arctos
- Brown bear, one
Tremarctos ornatus - Spectacled bear, one
Ursus
thibetanus - Asiatic black bear) were treated with one of the
following four protocols: (a) antigestagen J956 (Jenapharm), 10
mg/kg intramuscularly in late October and late November (two
bears); (b) EE2, 10 µg/kg bodyweight intramuscularly in
late October and late November (two bears); (c) AG/EE2
combination intramuscularly in late October and late November (two
bears); (d) AG/EE2 combination intramuscularly once in
mid November only (four bears). Sonographic examination of the
females in December showed that none of the bears were still
pregnant. In two bears, circumscribed hyperechoic areas in the
endometrium indicated resorption of implanted embryos. No side
effects (discomfort, vaginal discharge) were noted in any of the
bears. (P5.39.w9)
- At a dose rate of 7.5 - 10 mg/kg intramuscularly, given during
late diapause, antiprogestin J956 successfully prevented
implantation in
Ursus arctos
- Brown bear,
Melursus ursinus - Sloth bear
and
Tremarctos ornatus - Spectacled bear.
(J296.56.w1)
- Note: If the antiprogestin is given too late after implantation
(e.g. one month after implantation) there may be incomplete resorption of embryos, or fetal abortion.
It is therefore important to give the treatment in the late
diapause/early implantation period. (J370.57.w1,
P1.2002.w2)
- J956 intramuscularly at 10 mg/kg together with an
oestrogen (ethinyloestrodiol at 10 µg/kg) given after
implantation (mid-November or early December), resulted in
abortion, but in the two bears (Ursus arctos
- Brown bear) treated in December (late pregnancy), abortion
was incomplete. Also, two of the bears treated
post-implantation developed serosanguinous vaginal discharge
and discomfort. (J370.57.w1)
- Antiprogestins given orally were ineffective. (J370.57.w1,
P1.2002.w2)
- Oral (four doses each 10 mg/kg) or low-dose (1 mg)
intramuscular administration of antiprogestin J956 did not prevent
implantation and pregnancy. (J296.56.w1)
- Antiprogestin J956 can be delivered intramuscularly by remote
injection (darting). (J296.56.w1)
- At a dose rate of 10 mg/kg by intramuscular injection, plasma levels
of antiprogestin J956 were sustained (6.4 +/- 1.3 ng/mL) for nearly
two months in
Ursus americanus - American black bear. (J296.56.w1)
- Full information on fertility following antiprogestin treatment has
not yet been gathered. However, one bear treated with J956 and
ethinyloestadiol became pregnant a year after treatment. (J370.57.w1)
GnRH agonist in males
- An initial trial in a bear (Tremarctos ornatus - Spectacled bear)
indicated that this may be a useful method for contraception in bears
in the future. (P36.1994.w5)
- A GnRH agonist, leuprolide acetate (Leupron® Depot, TAP
Pharmaceutical, Chicago, Illinois, USA), injected subcutaneously
at 0.075 mg/kg/28 days in a male
Tremarctos ornatus - Spectacled bear
produced a reduction in testosterone levels in blood from 1.75 ng/mL
to less than 0.156 ng/mL, i.e. a 91% reduction. Within eight weeks of
cessation of treatment, levels returned to pre-treatment values.
The male was held adjacent to a female bear. (P36.1994.w5)
- If a GnRH agonist is used in seasonally-breeding bears, it needs to
be implanted about two months before the onset of the breeding season,
certainly at least six weeks before, so that any sperm produced have
been eliminated from the male before the female will ovulate. (D315)
- This treatment may reduce male aggression. (D315)
GnRH agonist in females
- This is particularly suitable for use in seasonal breeders. Because
of the initial stimulatory effect, the agonist needs to be implanted
about two months before the earliest possible onset of the breeding
season. Initial ovulation may be prevented by treating with a progestin
short term (e.g. oral contraceptives for about ten days) at the time
of the insertion of the GnRH agonist implant. (D315)
- Oestrous behaviour should be eliminated by use of a GnRH agonist. (D315)
- Note:
- GnRH agonists may cause abortion if used in pregnant females. (D315)
- The effects of GnRH agonist use on lactation have not been properly
tested. (D315)
|
| Lagomorph Consideration |
Physical separation
- Physical separation can be used to prevent breeding in lagomorphs. (B600.3.w3,
B601.1.w1,
P113.2005.w6)
Castration, ovariectomy/ovariohysterectomy and sterilization
(vasectomy/tubal ligation)
- Castration is effective at preventing breeding. Note: following castration, the
buck may remain fertile for at least four weeks and sometimes longer than this; the
buck should be kept apart from any does until six weeks after castration. (B600.3.w3,
B601.1.w1,
P113.2005.w6)
- Ovariohysterectomy is effective at preventing breeding. In pet
rabbits this is highly recommended because it also prevents development
of conditions such as
Endometrial Adenocarcinoma and other Uterine Neoplasia in
Lagomorphs
- Vasectomy can be carried
out in rabbits. Vasectomised males
are used sometimes to induce ovulation in female rabbits being
artificially inseminated. (B614.2.w2,
J35.151.w2)
- Tubal ligation can be carried out in rabbits. Experimentally,
surgical sterilisation, by tubal ligation, of 60 - 80% of wild
Oryctolagus cuniculus
- European rabbit populations in Australia, was shown
to reduce seasonal peaks of rabbit abundance, but did not reduce the
average adult population size. Sterilised females showed a much better
survival than unsterilised females (demonstrating the high costs
associated with reproduction), while unsterilised adults (males and
females) and immature rabbits also showed higher survival in the
sterilised population than in unsterilised populations. There was a
density-dependent increase in juvenile survival. (J182.37.w1,
J182.44.w1)
Immunocontraception using Zonae Pellucidae (ZP)
Proteins
- Immunization with intact or heat-solubilized porcine zonae
pellucidae together with various adjuvants has been shown to be
immunogenic, inducing a strong autoimmune response, and to cause
infertility, with failure to ovulate even after treatment with hCG,
and with development of ovarian pathology. (J371.25.w1,
J371.74.w1,
J531.21.w1)
- Immunization with whole rabbit zonae pellucidae failed to induce
infertility, although antibodies to zonae were found in the serum. (J371.25.w1)
- Recombinant rabbit zona pellucida glycoprotein B (ZPB), expressed in
eukaryotic cells in vitro was found to be an effective antigen
when injected with Freunds complete adjuvant. With the use of two
booster doses, sustained infertility was produced in 70% of female
rabbits; this required production of high antibody titres (at least
12,800). In male, but not female, rabbits, high antibody titres
developed after a single immunization. When ZPB was expressed in a
recombinant myxoma virus, serum antibody levels were similar in male
and female rabbits, but did not reach the 12,800 level; 25% of females
were infertile. Booster injections of recombinant ZPB protein resulted
in a higher antibody response and 80% infertility of female rabbits.
The primary mechanisms of infertility appeared to be degeneration of
oocytes and follicles. (J371.61.w2)
- Immunization with recombinant myxoma virus expressing rabbit zona
pellucida 3 (rZP3) glycoproteins resulted in production of serum
antibodies, binding of antibodies to zona pellucida from day 10,
transient inflammatory response in the ovaries, and infertility in 70%
of rabbits when first bred. Fertility later returned, as indicated by
pregnancy in 92% of rabbits at later matings (return to fertility
within two months). (J371.74.w1)
- Infection of rabbits with a recombinant myxoma virus expressing
rabbit zona pellucida protein B elicited a specific IgG response to
ZPB with the antibody binding strongly to the zonae pellucidae of
oocysts in both secondary and tertiary follicles. There were
significantly reduced preovulatory and tertiary follicles in the
ovaries at 30 days post infection. Histologically, in the medulla of
the ovary there were no follicles but a large number of probably
luteinized cells, indicating severe ovary pathology. (J20.318.w1)
- "In more recent experiments, recombinant myxoma viruses constructed with rZPC under the control of a synthetic combined early/late promoter induced infertility in 90-100% of rabbits mated 35 days after immunization and in 50% of rabbits at subsequent matings (Kerr, Perkins and van Leeuwen, unpublished results)."
(J532.71.w1)
|
| Ferret Consideration |
Castration,
Ovariohysterectomy and Vasectomy
Breeding in ferrets can be
prevented by surgical neutering: castration of males, ovariohysterectomy
(spaying) of females, or by vasectomy of males.
- Note: There is an increased risk of the development of adrenal gland disease
(Adrenocortical Neoplasia in Ferrets)
in early-neutered ferrets. It is recommended that ferrets (male or female)
be neutered only at puberty (6-8 months of age), not sooner and should be
implanted with a GnRH implant until fully mature. (W755.Sept11.w1)
- A study in the Netherlands found a significant correlation between
age of neutering and age of onset of adrenal disease. Within the
studied 1,274 ferrets, seven (0.55%) developed hyperadrenocorticism
confirmed by histological examination of excised adrenal glands while
a further seven were suspected cases based on clinical signs, but the
owners did not allow further studies to confirm the diagnosis. (J4.216.w2)
- Hyperadrenocorticism has been seen in entire (unneutered) ferrets,
but only rarely. (J4.216.w2)
- Vasectomy of males prevents fertilisation but does not affect
behaviour.
Preventing reproduction in entire females
Entire (fertile) jills which are not mated remain in oestrus throughout
the breeding season (until daylength decreases) and develop anaemia due to bone marrow suppression
caused by
Hyperoestrogenism in Ferrets.
(B627.8.w8,
W755.Sept11.w1)
If breeding is not required, it is important to end oestrus, not simply
prevent pregnancy. Options include:
- Mating with a vasectomised male (hoblet). (W755.Sept11.w1)
- Ferrets are induced ovulators; the physical stimulus of mating
results in ovulation. (J503.43.w1)
- It is recommended that each ferret owner keep their own hoblet,
rather than sharing a vasectomised male with others, in order to
reduce the risks of disease transmission. (W755.Sept11.w1)
- Proligestone
(the "jill jab")
- Proligestone
(0.5 mL Delvosterone, Intervet, subcutaneously) will
elicit ovulation. (B232.9.w9)
- This should be given in late March [northern hemisphere]. (J3.126.w7)
- Signs of oestrus start to reduce after three to four days. (J3.126.w7)
- If the initial 50 mg injection (0.5 mL of 100 mg/mL drug per jill,
subcutaneously) has no effect, give 25 mg seven days later, (B626.App.w22,
B631.21.w21)
and again 25 g seven days thereafter if necessary (should not be
needed). (B626.App.w22)
- Some jills return to oestrus later in the summer and require a
repeat injection. (J3.126.w7)
- Following injection with 40 mg proligestone in mid-February
[northern hemisphere], ferrets returned to oestrus in 99 +/-40
days (in April to July). Treatment later in the year (e.g.
late March) may prevent return to oestrus for the whole year
if ferrets are kept under natural light conditions. (J3.166.w1)
- Ferrets mated after returning to oestrus became pregnant
(3/4) or pseudopregnant (1/4). (J3.166.w1)
- Very occasionally a jill may return to oestrus a third or even a
fourth time in the same year. (J3.126.w7)
- Hormone-related alopecia develops in some treated ferrets. (J3.166.w1)
- Jills treated with proligestone can be bred as normal in
following years. (J3.126.w7)
- Note: Jills accidentally mated in May and June after being treated
with proligestone produced small litters (three and four kits); a
jill accidentally mated in July developed pseudopregnancy. (J3.126.w7)
- Medroxyprogesterone acetate (MPA)
- Following injection with 15 mg MPA in mid-February [northern
hemisphere], ferrets returned to oestrus in 94 +/-18 days (in May
to June). (J3.166.w1)
- Ferrets mated after returning to oestrus became pregnant (3/4)
or pseudopregnant (1/4). (J3.166.w1)
- Hormone-related alopecia develops in some treated ferrets. (J3.166.w1)
-
Human chorionic gonadotropin
(hCG) (Chorulon, Intervet), 20 - 100
units intramuscularly will induce ovulation. (B232.9.w9)
- Human chorionic gonadotropin hCG 100 IU can be given
intramuscularly after the 10th day of the vulva being swollen and
will induce ovulation. (B627.8.w8)
- Following injection with hCG in mid-February [northern
hemisphere], ferrets returned to oestrus after 53 days +/- 9 days
i.e. May to June. (J3.166.w1)
- Ferrets mated after returning to oestrus became pregnant
(3/4) or pseudopregnant (1/4). (J3.166.w1)
- Gonadotropin releasing hormone (GnRH) 20 µg can be given
intramuscularly after the 10th day of the vulva being swollen and will
induce ovulation. (B627.8.w8)
- Deslorelin acetate (gonadotropin-releasing
hormone agonist) in a slow-release formulation.
- Following implantation of deslorelin acetate in a slow-release
formulation in mid-February [northern hemisphere], jills showed
intensive signs of oestrus within four days, but signs stopped
within two weeks. They did not return to oestrus that year; first
oestrus occurred after 698 +/- 122 days (July of the year after
implantation to May of the year after that). (J3.166.w1)
- A new implant is needed about every 18 months or when
the jill shows signs of sexual activity. (W755.Sept11.w1)
Preventing reproduction in entire males
Vasectomy prevents males from fertilising females, but does not reduce
odour, nor does it change behaviours such as aggression towards other
males.
- Deslorelin acetate (gonadotrophin-releasing hormone agonist) in a
slow-release formulation may be given to males as a form of "chemical castration". (J296.70.w1)
Experimentally, males with such an implant (9.4 mg deslorelin per
ferret) were shown to have reduced plasma FSH and testosterone
concentrations, reduced testis size, and reduced musky odour (lower
odour even than in surgically castrated males). Spermatogenesis was
suppressed (no germ cells present). This appeared to be a useful
alternative to surgical castration. (J296.70.w1)
- Treatment of entire male ferrets with deslorelin (GnRH agonist)
implant greatly reduces sexual behaviours. Treated ferrets also showed reduced
intermale aggressive behaviour (more so than surgically castrated
ferrets), and increased play behaviours. (J288.115.w1)
- If two entire (uncastrated) males are to be kept together, then
implanting both deslorelin is advisable to reduce breeding season
aggression and territoriality. (W755.Sept11.w1)
|
| Bonobo Considerations |
Given the small size of the
captive bonobo population, and the associated potential need for breeding
by any bonobo, contraception should be used only as a last resort;
separation of individuals by moving one to another group is preferable if
particular pairings need to be avoided. Any method of contraception used
should ideally be reversible. (D386.5.w3e)
- In general, methods used in humans should be considered. It is
likely that contraception methods usedd in Pan troglodytes
would be appropriate for use in bonobos. (D386.5.w3e)
Males
- At present, there are no reliable methods available for reversible
contraception of male bonobos. (D386.5.w3e)
- Vasectomy can be used for male contraception, but is not reliably
reversible and therefore this is not recommended. (D386.5.w3e)
- Ligation of the vas deferens by use of surgical clips would be a
possible method and preferable to vasectomy. Risks include that this
is a surgical procedure, requiring anaesthesia; the risk of infection;
and the possibility of spontaneous reversal by recanalisation of the
vas deferens, such that frequent follow-up analysis of ejaculate
obtained by electrostimulation or via an artificial vagina is
required. (D386.5.w3e)
- This method has been used in bonobos. (P1.2002.w10)
Females
- Melengestrol acetate (MGA) implants have been used in Pan troglodytes - Chimpanzee
and in Pongo pygmaeus - Orang-utan,
generally with a high success rate although with some failures in Pongo pygmaeus - Orang-utan
due to imlant loss associated with allogrooming. Tagging the implant
with a microchip transponder would allow earlier detection of implant
loss. Unwanted effects include definite weight gain and a possible
link with development of diabetes. (D386.5.w3e)
- Levonorgestrel implant (Norplant) has been used successfully in Pan troglodytes - Chimpanzee
and in Pongo pygmaeus - Orang-utan.
If placed deeply and with complete sterility, retention is good.
Reintroduction of the animal to the group should be delayed until the
site has completely healed, to minimise the risk of implant loss
during allogrooming. This method is more likely to fail in obese
individuals. There is an unknown risk of long-term impairment of
fertility, but this method could be used. (D386.5.w3e)
- Medroxyprogesterone acetate (DepoProvera) has been used in Pan troglodytes - Chimpanzee
successfully. It is administered by intramuscular injection, either by
dart or with the animal anaesthetised. It is important that the whole
dose is given. The effects of long-term use are unknown and this would
be recommended only for short term (less than six months) use. (D386.5.w3e)
- Birth control pills have been used in great apes, but there is
always a risk of incomplete compliance with taking the pills,
therefore their routine use is not recommended. (D386.5.w3e)
- Intrauterine devices (IUD) have been used in Pan troglodytes - Chimpanzee;
the smallest human size (suitable for a nulliparous woman) should be
fitted. To reduce the risk of the female removing the device, the
removal strand can be shortened; obviously this makes removing it,
when this is wanted, more difficult. A failure rate of about 5% should
be expected and there is a risk of complications if the individual
becomes pregnant while the device is in place. (D386.5.w3e)
- Low-dose oestrogen oral contraceptive pills have been used in bonobos; problems of breakthrough bleeding have been reported. (P20.2010.w1)
|
| Associated techniques linked from Wildpro |
|
