Biomedical Engineering Reference
In-Depth Information
(
Akseletal.,1985
). Serum progesterone concentrations
greater than 100 ng/ml can be used to identify cycling
squirrel monkeys.
Yeoman et al. (2000)
found a mid-cycle
follicle stimulating hormone (FSH) rise coincident with
the LH surge as well as elevations in circulating FSH
during the luteal phase, suggesting that considerable
follicular development occurred prior to luteolysis.
Average gestation length in squirrel monkeys is 150
e
155
days.
These hormonal changes, consistent with estrous
cycles, were associated with behavioral changes (
Williams
et al., 1986
). The female squirrel monkeys with cyclic
hormonal levels received more genital investigations and
more sexual invitations than did noncycling females.
Cycling females also showed changes in their behavior,
tending to follow the male more than noncycling females
did and to sniff the male more frequently. Copulations
occurred on the day of and day following ovulation.
Squirrel monkeys adapt to many different social group
configurations. For breeding purposes, squirrel monkeys do
well in single-male/multi-female groups with ratios as high
as 1 male to 10
e
12 females. Infants begin to eat solid food
at around 1 month of age and will stop nursing at 4
e
5
months. Squirrel monkey females show a high rate of
allomaternal care, with unrelated females carrying and
nursing infants as old as 6 months (
Williams et al., 1994
).
Since squirrel monkey infants are large (up to 18% of the
dam's nonpregnant body weight), allomaternal care may be
an important strategy to increase infant survivability.
Squirrel monkey females reach their maximum repro-
ductive potential between the ages of 6 and 13 years. In
females younger than age 4, fetal and neonatal mortality is
high. Although females can produce healthy infants later
into their teens, their probability of becoming pregnant
decreases with age. The generation time for squirrel
monkey females is approximately 9 years, with females
producing 5
e
10 surviving infants during their lifetime.
a factor in keeping groups apart (
Moynihan, 1964
).
Agonistic encounters involve back arching, stiff-legged
jumping, pilo-erection, urination and defecation, and
giving clicking/grunting alarm calls. Identical agonistic
displays occur between conspecifics and other species
(
Wright, 1989
). They have loud contact calls (
Moynihan,
1976
). Olfaction is an important component of communi-
cation, and Aotus marks substrates by rubbing a gland at
the base of its tail and exuding a brown, oily substance
(
Wolovich and Evans, 2007
).
Owl monkeys are typically described as nonseasonal
breeders in captivity, although some field data suggest that
these animals can show seasonality in habitats with extreme
environmental fluctuations (
Fernandez-Duque and
Huntington, 2002
). Two birth peaks per year have been
noted in the field
e
one at the end of the dry season and the
other in the middle of the wet season (
Wright, 1985
).
Females cycle approximately every 16 days (
Bonney et al.,
1979
). The mean age of first birth in Aotus females is
3 years (
Gozalo and Montoya, 1990
). Gestation is 133
e
141
days (
Gozalo and Montoya, 1990
). Owl monkeys have
a relatively short interbirth interval of about 1 year, which is
possible owing to the high levels of paternal care that
alleviate much of the energy burden to the mother (
Garber
and Leigh, 1997
).
Although there are no data on female puberty in owl
monkeys, male puberty begins around 13
e
15 months of
age (
Dixson et al., 1980
). In field studies, young males tend
to disperse at the age of 2
e
3 years (
Fernandez-Duque and
Huntington, 2002
) and may pass into a nomadic,
“vagabond” stage before pair-bonding with a female. Once
animals reach 18
e
24 months of age, they can be paired to
form new breeding groups. Male
e
female pairings are
successful in approximately 75
e
80% of attempts.
Isosexual pairs can be established but are more difficult; up
to 65% of female
e
female pairs and 44% of male
e
male
pairs are successful.
Owl Monkeys
Owl monkeys are usually reported as highly monogamous
nonhuman primates, with groups most often composed of
an adult male and female and up to three infants and
juveniles (
Wright, 1981
). The sire provides most of the care
for the infant and only gives the infant to the dam to nurse
(
Jantschke et al., 1998
). If the father dies when the infant is
still young, other siblings, but not the mother, will assume
the caregiver role. Owl monkeys are unique in that the
female will actively refuse to carry the young if the male is
unavailable, going so far as to violently pull the infant off
its back.
Owl monkeys are highly territorial and have extremely
small home ranges given the size of this nonhuman primate
(
Wright, 1989
). Male
e
male aggression is common and is
Marmosets
Marmosets and tamarins are small, South American
primates of the subfamily Callitrichidae. The only calli-
trichine species commonly used in biomedical research is
the common marmoset (Callithrix jacchus). Recent reviews
of standard husbandry and management practices for
breeding marmosets include those of
Tardif et al. (2003),
Layne and Power (2003)
, and
Rensing and Oerke (2005)
.
Sexual maturity
e
as defined by occurrence of ovula-
tion in females and ejaculation of motile sperm in males
e
occurs at 11
e
13 months of age. However, ovulation may be
suppressed for periods of years following puberty under
certain conditions (
Abbott, 1987; Tardif et al., 1994
).
A standard recommendation is that animals not be paired
for breeding until around 18 months of age, as successful
