Laboratory macaques: When to wean?

Abstract

Worldwide there is large variation in the age at which young macaques destined for use in research are permanently separated from their mothers, and in the subsequent social environment in which they are reared. This stems from variation in minimum weaning ages and rearing practices in guidelines on laboratory animal care and use, as well as from scientific, business and other considerations. This article summarises the literature on the effects of weaning policy on the behavioural and physical development of macaques, supplemented with production data from breeding colonies of rhesus and long-tailed macaques. The aim is to help guide decision-making to improve animal welfare and quality of science. On the basis of the evidence reviewed here, unless there is strong justification for artificial weaning on scientific or animal health grounds, it is preferable for young macaques to remain with their mothers until they have become behaviourally independent. Minimum weaning age should therefore not normally be less than 10–14 months old, but weight, health and behavioural criteria should be used to determine the most appropriate weaning age for the welfare of each individual monkey.