Lactational performance of various mammalian species

Lactational performance varies widely among mammalian species. Lactation plays a variable role in the overall reproductive strategy. The fraction of total growth and development of the young contributed by lactation is minimal in such species as guinea pigs but is a very high proportion in some marsupials and primates. Although the overall daily capacity for transfer of energy for many species is rather constant at about 125 kcal/kg body weight.70, the proportions of nutritive constituents in milk differ greatly among species and vary during lactation.