UC Davis

Significant relations were observed between select infant-care and weaning behaviors and growth in body weight in common marmoset monkeys (Callithrix jacchus). The patterns of these relations suggest that earlier occurrence of developmental milestones, such as cessation of transport (being off carriers) and weaning to solid food, were associated with slower growth during the subsequent period. In contrast, more frequent nursing bouts during the period in which weaning was initiated were associated with higher growth rates. In the case of being off carriers, these effects did not carry over to older ages, suggesting that any deficits in growth were temporary. In the case of earlier, more frequent consumption of solid food, there was some suggestion that there were longer-term effects, followed by catch-up growth. The knee-to-heel length of subjects was not related to the measured behaviors. There was no relation between early weaning to solid food and leanness at day 75, suggesting that, although this behavior was affecting overall weight, it did not affect relative gains of fat versus lean mass. There were, however, significant correlations between cessation of transport or frequency of nursing bouts during the weaning period and leanness, with earlier cessation of transport and less frequent nursing associated with leaner infants, after weaning. Our results differed from those of a previous study that found a relation between linear growth and abuse in this species, with abuse defined as physical injury by other members of the group. We found no differences in growth between abused and nonabused infants. However, abused infants had lower birth weight.