Abstract # 91:

Scheduled for Saturday, September 17, 2011 07:00 PM-09:00 PM: Session 14 (Salon G (Sixth Floor)) Poster Presentation


CALCIUM AND PHOSOPHORUS IN MILK ARE ASSOCIATED WITH MATERNAL PARITY AND INFANT SEX IN MACACA MULATTAS

A. B. Foster1, L. M. Landis2, D. Rendina1 and K. Hinde1,3
1California National Primate Research Center, University of California Davis, One Shields Avenue, Davis, CA 95616, USA, 2Western Washington University, 3Department of Human Evolutionary Biology, Harvard University
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Mother’s milk provides the building blocks necessary for infant development and growth. Here we investigate calcium (Ca) and phosphorus (P) concentrations in milk, and the ratio of Ca/P, all critical for infant skeletal development. Ca concentrations in milk do not reflect maternal dietary intake but are mobilized from body stores and are expected to diminish over time. Indeed maternal parity in captive rhesus macaques at the CNPRC (N=107) was significantly and negatively correlated with both Ca and P concentrations in milk at peak lactation (r=-0.16, p=0.05 and r=-0.2, p=0.02, respectively). Moreover parity was a more meaningful biological measure than was maternal age. Additionally, we investigated sex-biased concentrations of these minerals, without a clear prediction of the directionality of the effect. Although infant males are bigger and grow faster, skeletal epiphyseal calcification occurs earlier for infant females. However, calcium in milk is highly correlated with protein (r= 0.78, p<0.0001), and previous research from this colony has demonstrated that mothers of sons produce higher protein concentrations in their milk. Using multiple regression, we found that mothers rearing daughters produced significantly higher Ca/P ratios in milk than did mothers rearing sons, after controlling for maternal parity, protein (%), and infant mass (B=-0.09, two-tailed p=0.04, F4,102=6.4). These results suggest that milk Ca/P ratio contributes to the accelerated skeletal development of infant females. Research supported by NSF BCS-0921978 and BCS-0525025