Proximate composition (moisture, lipid, protein, ash), vitamin A and v
itamin E content, and six minerals (Cu, Fe, Zn, Mg, Mn, Ca) were measu
red in quail, rats, mice, and guinea pigs raised on at least two diffe
rent diets per species. Feed composition varied substantially but erra
tically in lipid, vitamin A, vitamin E, and mineral content. All unsup
plemented feeds had less vitamin E than NRC recommendations and most f
eeds contained less Mn than recommended. Most feeds deviated from the
manufacturer's guaranteed analysis. There were significant effects of
diet on body mass, moisture, lipid, ash, vitamin A, vitamin E, Ca, and
Cu content for quail. There was a significant effect of diet on vitam
in A content of mice; there were no other effects of diet on mammalian
species. There was no correlation between diet composition and body c
omposition for any species. Rats and mice differed significantly in vi
tamin A, Fe, and Cu content when raised on the same diet. We suggest t
hat (1) it is difficult to assume or assess composition or adequacy of
commercial diets without laboratory analysis, (2) supplementation of
diets with whole foods can potentially reduce diet quality, (3) nutrie
nt differences in quail are related to differences in growth, and such
age-related differences may be more important in determining nutrient
content than diet, (4) there were significant species differences in
responsiveness to changes in diet, and (5) whole domesticated prey are
a potentially inadequate source of vitamin E for raptors and of Mn an
d Cu for all carnivores. (C) 1996 Wiley-Liss, Inc.