Biomedical Engineering Reference
In-Depth Information
be good breeders, males must exhibit authority to maintain
social harmony.
Baboon breeding arrangements have been described by
Else et al. (1986)
and
Ha et al. (2000a,b)
. Baboons breed
best in harems, though they may also be maintained in very
large multi-male, multi-female groups with sufficient
space. Optimal productivity has been found with breeding
groups of a single male and 10
e
15 females (K.S. Rice,
personal observation). Stable breeding groups with little
movement in or out maintain social stability and help
minimize the chance of miscarriage. A single male breeder
also tends to maintain social harmony among his group
members such that the best success is achieved by intro-
ducing females in small groups instead of one by one. Good
integration is experienced by introducing a small group of
new females to the male and allowing them to socialize for
several hours, then returning the main group of female
breeders to the group cage. Although establishing social
rank may necessitate some physical altercations, the male
is more apt to promote integration because of the bonds
established by introducing new females in this manner.
Baboons are predictable in their behavior, generally
calm, and easy to handle in captivity. Since baboons
tolerate weather extremes well, they can be housed in
outdoor facilities in most environments. The types of
outdoor large group housing used for the SNPRC colony
afford easy access to the animals and allow moderately
large social groups (up to 20 animals)
ages. Based on this scenario and on knowledge of mortality
(life-table analysis) and reproduction (e.g. animal age at
first pregnancy, prime reproductive years, stable breeding
group design), an optimal breeding colony size can be
identified. Other factors to consider are recovery periods
for surgical interventions (e.g. catheter implant for tether
studies, fectectomy or caesarean section), sufficient reserve
male breeders, and facility renovation plans that may affect
breeding space.
Squirrel Monkeys
Squirrel monkeys have a distinct breeding season that spans
approximately 3 months followed by a birth season
approximately 5 months later (
Williams et al., 2002
).
Seasonal breeding has been related to annual rainfall cycles
and seasonal food availability (
Baldwin and Baldwin,
1981; Boinski, 1987
), changes in light cycle (
Rosenblum
and Cooper, 1968
), and relative humidity (
DuMond, 1968
).
Boinski (1987)
found a strong tendency toward birth
synchrony in Saimiri oerstedii in Costa Rica and suggested
this tendency might be an anti-predator adaptation.
During prebreeding and breeding season, male squirrel
monkeys undergo marked physical changes including
increases in body weight, spermatogenesis, and circulating
levels of androgens (
Wiebe et al., 1984, 1989
). The increase
in body mass is distributed primarily over the upper torso
(
DuMond and Hutchinson, 1967; Williams et al., 1986;
Boinski, 1987
) and is related to the increased levels of
androgens (
Nadler and Rosenblum, 1972; Coe and
Rosenblum, 1978
). These annual weight gains begin during
the third year of life; however, most laboratories do not
consider a male squirrel monkey to be sexually mature until
he is 4 years old.
Along with the physiological changes in adult male
squirrel monkeys there are behavioral changes (
Williams
et al., 1986
). Sexual interactions between males and
females are not seen during the nonbreeding season. The
breeding season is characterized by increased levels of
sexually related responses such as genital displays, ano-
genital inspection, and copulation. The breeding season is
characterized by a reduction in aggressive responses
compared with prebreeding season levels.
Female squirrel monkeys have an unusually short
ovarian cycle that is characterized by exceptionally high
circulating steroid hormones (
Ghoshetal.,1982;Aksel
et al., 1991
). Females are seasonally polyestrous, with
each cycle spanning 10
e
12 days (
Diamond et al., 1984;
Akseleta ,1985
). Although there are no obvious,
external signs of estrous, the female's cycle can be
monitored by the cytology of vaginal epithelial cells
(
Travis and Holmes, 1974
), by ultrasound monitoring of
follicular development (
Schuler et al., 2007
), or by
monitoring circulating levels of
that closely
approximate a natural setting.
When a new breeding group is started, the group is
allowed the first 3 months to acclimate, after which
a pregnancy rate of about 80% is expected. Females who do
not become reproductive can be moved into another group
with success. Sometimes it helps to move low-ranking or
more submissive females to groups with younger females.
Other factors to monitor are pregnancy retention, live
births, and successful mothering. A relatively common
phenomenon in harem groups is for a more dominant
female to “steal” another female's infant, in which case it is
difficult, if not impossible, for the mother to retrieve her
infant. If a female steals another mother's infant, the
practice has been to retrieve the infant and put the baby
back on the mother. If it happens again and the baby stealer
is lactating, she is allowed to keep the infant. Females are
kept in breeding, and about three pregnancy losses or three
infant deaths are allowed before that baboon is removed
from breeding. SNPRC keep infants with their mothers for
a minimum of 9 months. From practice, this seems to
promote the best environment for producing offspring that
will have normal behavior.
The best guide to population management in baboons
may be medium-term supply and demand. Evaluation of
the demand for animals over a 5- to 10-year span will help
to determine the numbers of animals needed at specific
serum progesterone
