depending upon the product label. To ensure that label claims will be met, manufacturers often incorporate excesses of some nutrients to account for loss during production, storage, and use.
Formulas Used for Artificially Rearing Infant Nonhuman Primates
Early on, it was found that milk formulas intended for human infants could be used to rear some newborn nonhuman primates (Table 9-5). Originally, human-infant formulas were used to ensure survival of newborn monkeys that had lost their mothers. That was successful, and it was soon recognized that artificially reared (formula-fed) nonhuman primates could be used as animal models for studies of nutrition, growth, and development of human infants (Ausman et al., 1977, 1986, 1989; Samonds and Hegsted, 1973, 1978). For some nonhuman-primate species, however, the proportion of metabolizable energy provided by protein (usually 5-10%) was too low, and protein malnutrition was induced, since those species normally produce milk in which protein accounts for 12-16% of metabolizable energy. Later, higher-protein diets that successfully nourish these infants were developed (Samonds and Hegsted, 1978; Ausman et al, 1989).
It is difficult to prepare liquid diets in the laboratory that keep nutrient sources in a homogeneous suspension. Some particles precipitate and others float, causing varia-