Studies with timed-pregnant squirrel monkeys (Saimiri sciureus)

Area of Science:

• Primate reproductive biology
• Colony management
• Animal behavior

Background:

• Establishing breeding colonies of nonhuman primates is crucial for research.
• Saimiri sciureus (squirrel monkeys) are widely used in biomedical research.
• Understanding reproductive parameters in nonhabituated colonies is essential for successful breeding programs.

Purpose of the Study:

• To document reproductive parameters in a large, nonhabituated colony of Bolivian squirrel monkeys (Saimiri sciureus).
• To assess insemination rates, gestational periods, and early pregnancy outcomes.
• To identify factors potentially contributing to low birth rates in such colonies.

Main Methods:

• A large colony of 373 female and 40 male Saimiri sciureus was established.
• Insemination was determined by sperm presence or vaginal plug detection.
• Pregnancy was monitored, and gestational periods were recorded.
• Early pregnancy loss was evaluated using mouse bioassays.

Main Results:

• 74% of females (277/373) showed signs of insemination.
• 46 full-term progeny were delivered with a mean gestational period of 152.5 days.
• The median time to insemination was 5 days under continuous cohabitation.
• High rates of early embryonic resorptions were detected within the first 50 days of gestation.

Conclusions:

• Squirrel monkeys in nonhabituated colonies exhibit high insemination rates.
• Significant early pregnancy loss (resorptions) may be a key factor limiting birth rates.
• These findings provide insights into reproductive challenges in nonhabituated primate colonies and inform future breeding strategies.