Behavioral management of specific pathogen-free rhesus macaques: group formation, reproduction, and parental competence.

Breeding colonies of specific pathogen-free (SPF) rhesus macaques were established to eradicate the transmission of Herpesvirus simiae and several retroviruses in this species. Strategies to attain this goal included the combination of large numbers of monkeys into groups, the establishment of small unimale groups, and a program using animals that were temporarily socially restricted. All methods required the establishment of new social groups from unfamiliar animals. In using these methods, we encountered important behavioral questions related to the group formation process, as well as reproductive and parental competence. Age and prior social experience were important determinants of social and parental success. New multimale-multifemale SPF group formations were successful initially and involved the least aggression during the first breeding season when young females and older males were used. Formation of unimale groups was successful, even when males and females were of similar ages. Breeding competence did not seem to be affected by any of the SPF colony management procedures, but animals with restricted early social experience exhibited impaired parental competence when compared with animals with more social experience. Males were more sensitive to the effects of early social restriction than females. A variety of behavioral obstacles will be encountered when attempting to establish an SPF breeding colony by forming groups by use of these methods. Skilled behavioral management is necessary to surmount these obstacles and to achieve satisfactory social integration, reproduction, and parenting.