Rhesus macaque milk: Magnitude, sources, and consequences of individual variation over lactation

Authors

  • Katherine Hinde,

    Corresponding author
    1. Department of Anthropology, UCLA, Los Angeles, CA
    2. California National Primate Research Center, Davis, CA
    • Department of Anthropology, UCLA, 341 Haines Hall, Box 951553, Los Angeles, CA 90095-1553, USA
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  • Michael L. Power,

    1. Research Department, American College of Obstetricians and Gynecologists, Washington, DC
    2. Nutrition Laboratory, Smithsonian National Zoological Park, Washington, DC
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  • Olav T. Oftedal

    1. Nutrition Laboratory, Smithsonian National Zoological Park, Washington, DC
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Abstract

Lactation represents the greatest postnatal energetic expenditure for mammalian mothers, and a mother's ability to sustain the costs of lactation is influenced by her physical condition. Mothers in good condition may produce infants who weigh more, grow faster, and are more likely to survive than the infants of mothers in poor condition. These effects may be partially mediated through the quantity and quality of milk that mothers produce during lactation. However, we know relatively little about the relationships between maternal condition, milk composition, milk yield, and infant outcomes. Here, we present the first systematic investigation of the magnitude, sources, and consequences of individual variation in milk for an Old World monkey. Rhesus macaques produce dilute milk typical of the primate order, but there was substantial variation among mothers in the composition and amount of milk they produced and thus in the milk energy available to infants. Relative milk yield value (MYV), the grams of milk obtained by mammary evacuation after 3.5–4 h of maternal-infant separation, increased with maternal parity and was positively associated with infant weight. Both milk gross energy (GE) and MYV increased during lactation as infants aged. There was, however, a trade-off; those mothers with greater increases in GE had smaller increases in MYV, and their infants grew more slowly. These results from a well-fed captive population demonstrate that differences between mothers can have important implications for milk synthesis and infant outcome. Am J Phys Anthropol 2009. © 2008 Wiley-Liss, Inc.

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