No Effect of Infant Nursery Rearing on Laboratory Rhesus Monkey Dams' Social Behavior or Long-Term Cortisol Profiles.

Area of Science:

• Primate behavior
• Animal welfare science
• Reproductive endocrinology

Background:

• Nursery rearing (NR) of infant primates is common in research, but its impact on dam welfare is unknown.
• Animal advocacy groups raise concerns about mother-infant separation due to NR, potentially influencing research policy.
• Lack of empirical data necessitates investigation into dam responses to infant NR versus mother-peer-rearing (MPR).

Purpose of the Study:

• To investigate the behavioral and hormonal effects on rhesus macaque dams when their infants are nursery-reared (NR) or mother-peer-reared (MPR).
• To provide evidence-based insights into dam welfare concerning infant rearing practices in laboratory settings.

Main Methods:

• Behavioral observations (social, self-care, exploration, abnormal behaviors) were conducted on 49 rhesus macaque dams for 30 days pre- and post-partum.
• Infants were randomly assigned to NR (N=27) or MPR (N=22) conditions.
• Hair cortisol concentrations were analyzed across three periods: pregnancy, neonatal, and peak lactation.

Main Results:

• No significant gross behavioral differences were observed between dams of NR infants and dams of MPR infants (p>0.05).
• Dams of MPR infants exhibited expected post-partum behavioral shifts (increased social grooming, decreased foraging).
• No differences in hair cortisol concentrations were found between dams of NR and MPR infants across the study period (p>0.05).

Conclusions:

• Nursery rearing of infant macaques does not appear detrimental to dam welfare based on assessed behavioral and endocrine measures.
• The findings suggest current nursery rearing practices are compatible with maintaining dam well-being in laboratory settings.
• This study provides crucial data to inform policy decisions regarding nonhuman primate infant care and research ethics.