Abstract # 205:

Scheduled for Saturday, August 19, 2006 08:00 AM-10:30 AM: Session 19 (Regency East #2) Symposium

Sources of variation in milk composition: phylogeny, life history, and maternal condition.

M. L. Power1,2
1Smithsonian National Zoological Park, Nutrition Laboratory, Departmen of Conservation Biology, Washington, DC 20008, USA, 2Research Department, American College of Obstetricians and Gynecologists, Washington DC 20024, USA
     Lactation is a defining characteristic of mammals. It arose before the divergence of monotremes, marsupials and eutherian mammals, and thus predates the adaptation of live birth. A remarkable number of lactation strategies have evolved. For example, mammalian milks range in fat content from 50% in some marine mammals to under 1% in Perissodactyls. The lactation strategy of a species is the integration of the duration of lactation, the frequency of suckling, the volume of milk produced per day, and the composition of that milk. All these aspects must work together to meet the nutrient requirements of infants while not exceeding maternal capacity. Primates in general have relatively long lactations, nurse their infants frequently, and produce large quantities of dilute milk. Within this general pattern there is variation among species that may reflect both phylogeny and infant care patterns. For example, human milk is more similar to chimpanzee milk than it is to macaque milk. Some prosimians produce higher fat milks; this may be an adaptation to their habit of parking infants in nests, reducing the frequency of nursing. Several primate species produce relatively invariant milks (e.g. apes, lemurs). Other primate species appear to produce more variable milks that may depend on female condition (e.g. rhesus macaque, common marmoset). Even among variable milks, however, there appear to be aspects of constancy, which may reflect phylogentic constraints.