DETERMINANTS OF POSTNATAL WEIGHT IN INFANT RHESUS-MONKEYS - IMPLICATIONS FOR THE STUDY OF INTERINDIVIDUAL DIFFERENCES IN NEONATAL GROWTH

This paper provides an analysis of infant body weights obtained from a sample of 38 rhesus monkey infants (Macaca mulatta) aged 29-165 days, i.e., animals still nutritionally dependent on their mothers. We exam ine the data on neonatal weights in relation to a number of factors, m ost notably, the sex of the infants, and the age and adiposity of thei r mothers. The infant body weights represent cross-sectional rather th an longitudinal data; because they were mostly free-ranging animals, t he infants were weighed just once each. Nevertheless, the results of o ur analysis strongly suggest that early postnatal growth in free-rangi ng rhesus is dependent on both maternal fatness and age. They also sug gest that, although male infants are generally heavier than like-aged female infants, they do not grow any faster during the early postnatal period. Here, we speculate that the associations between infant size and both maternal age and adiposity are the result of between-mother d ifferences in lactational output. (C) 1995 Wiley-Liss, Inc.