Biomedical Engineering Reference
In-Depth Information
TABLE 8.4
Reproductive Rates for Macaques Housed Under Different Captive Conditions
Pregnancy Rate
a
Loss Rate
a
Production Rate
a
Species
Breeding Configuration
Reference
M. mulatta
Free-ranging, provisioned
80.3
4.3
71.3
Rawlins and Kessler, 1986
M. mulatta
Outdoor corral
73.3
13.6
NA
Hendrickx and Dukelow,
1995
M. mulatta
Gang caged harems
55
9
43
Westergaard et al., 2000
M. mulatta
Outdoor corral
80
6
69
Westergaard et al., 2000
M. fascicularis
Indoor-outdoor harems
53
22
31.8
Gardin et al., 1989
M. fascicularis
Indoor, single housing, F
0
57.9
12.8
47.4
Honjo et al., 1984
M. fascicularis
Indoor, single housing, F
1
36.8
14.6
28
Honjo et al., 1984
M. fascicularis
Free-ranging, unprovisioned
68
NA
NA
Crockett et al., 1996
a
Percentage, see text for definition of terms.
Data from long-term reproduction programs have been
fruitfully used to assess the variation in output from
nonhuman primate populations that need to be self
sustaining.
Ha et al. (1999)
provide a detailed analysis of
reproduction in pig-tailed macaques (Macaca nemistrina)
based upon 30 years of breeding records from the University
of Washington's nonhuman primate research center. This
analysis indicated that for this species, the presence of the
sire and of other pregnant females in the group increased the
probability of viable births while more frequent animal
moves in and out of groups as well as lower parity decreased
the probability of viable births. Sire presence was the single
most important factor in most measures of reproductive
outcome.
Crockett et al. (1996)
evaluated the value of
computer simulations of population dynamics as a means to
manage harvesting rates from a population of simian
retrovirus-free cynomolgus macaques established on Tinjil
Island, Indonesia. The simulation was used to determine that
at intermediate birth and survival values that reflected the
actual birth and survival rates, the island population of these
animals would be approaching carrying capacity and that at
high rates, the rate of harvesting from this animal population
would need to be increased in order to not overpopulate the
island, or provisioning would need to begin. This “herd
management” approach can, then, be successfully employed
with free-ranging breeding populations.
Various strategies may be employed during the forma-
tion of new breeding groups regardless of which type of
housing conformation is used. Groups can be formed by
introducing all the members at once or by incrementally
adding animals in small numbers until the desired pop-
ulation is attained. Animals can also be introduced to each
other in an environment in which there are barriers that
allow sight and touch between individuals but prevent
complete contact, or animals can be introduced to an
environment without barriers. A study performed at Labs of
Virginia (
Westergaard et al., 1999
) investigated the role
different group formation practices had on rhesus aggres-
sion and reproductive performance. Results suggested that
incremental addition of animals in small groups to the
population in an enclosure with barriers that do not permit
immediate contact decreased the incidence of aggression,
trauma, and death. However, group formation strategy did
not appear to have any effect on reproductive rates.
In addition to employing strategies to minimize
aggression and trauma and to promote reproductive
performance, colony managers must also be cognizant of
maintaining genetic diversity. An essential component of
this is maintenance of superlative parentage and medical
records. Molecular techniques such as DNA fingerprinting,
analysis of DNA restriction length polymorphisms
(RFLPs), short tandem repeats (STR), or single nucleotide
polymorphisms (SNPs) are frequently employed to confirm
parentage and assess the degree of genetic diversity (
von
Segesser et al., 1995; Kanthaswamy and Smith, 1998,
2002; Kanthaswamy et al., 2009, 2010; Trask et al., 2011
).
Various management practices can be utilized to promote
genetic diversity or minimize loss. These include fostering
infants from one matriline onto dams in another matriline,
removal of males after a designated number of breeding
seasons, removal of complete matrilines, introduction of
new males, or increasing the male:female ratio. Another
possible method for increasing diversity is to select males
for breeding who possess rare genetic alleles. However,
because any procedure that alters the population dynamics
within groups has the potential to result in aggression and
trauma, the benefits of increasing genetic diversity must be
balanced with the potential social impact.
