Abstract # 210:

Scheduled for Saturday, August 19, 2006 10:00 AM-10:30 AM: Session 19 (Regency East #2) Oral Presentation

Variability in the composition of milk of common marmosets: effects of maternal size, litter size and energy balance

S. D. Tardif1, M. L. Power2,3 and O. T. Oftedal2
1Southwest National Primate Research Center, P.O. Box 760549, San Antonio, TX 78245-0549, USA, 2Smithsonian's National Zoological Park, 3American College of Obstetricians and Gynecologists
     Reproduction in female common marmosets (Callithrix jacchus) has been shown to be sensitive to energy stores and energy balance. Females with higher body fat are more likely to triple ovulate instead of the normal double ovulation. Females that lose weight early in gestation abort their pregnancies. Lactation is also affected. The composition of marmoset milk is quite variable, even among different litters for the same female. Gross energy (GE) content of milk ranged between 0.49 kcal/g and 1.2 kcal/g. There are effects of both maternal condition and litter size. Small mothers nursing twins produce low energy milk. This result may reflect energy balance. Females that lost weight during lactation produced the lowest energy milks while females that gained weight during lactation produced high fat, high energy milks. Fat and protein content of milk are positively associated while both are negatively correlated with sugar concentration. Thus, depending on initial maternal condition, litter size and weight change during lactation, marmosets produce different milks. The milk could have low GE, with most of the energy being provided by the sugar content. For high GE milks most of the energy comes from fat. Intriguingly, the proportion of GE from protein is relatively invariant, at about 19.5%. This last result appears to hold true for both pygmy marmosets and golden lion tamarins, suggesting that it might represent a phylogenetic constraint.