Reinhardt, V. 2002. Artificial weaning of Old World monkeys: Benefits and costs. Journal of Applied Animal Welfare Science 5(2), 151-156.

The perceived benefits of permanent, pre-weaning mother-infant separation are not supported by scientific findings. ... As long as there is an excessive number of monkeys and insufficient cage space, there is no ethically legitimate reason for attempting to enhance the animals reproductive output, especially when such measures are not proven to be effective but cause unequivocal psychological distress. ... It is conceivable that maternal-infant separation for the purpose of artificial weaning flaws primate husbandry to the exent of increasing - rather than decreasing - the total number of monkeys needed for research. Thus, artificial weaning is not only an avoidable source of distress but it may also be an economically unsound management practice.