A comparison of the response of woodchucks and rats to variations in dietary lipotrope and lipid content.

A soy protein-based experimental diet for woodchucks (Marmota monax) is described. The diet supported growth of juvenile woodchucks for 12 wk. With this diet, the effects on both woodchucks and rats of increasing dietary corn oil from 5 to 15% and of deleting supplemental lipotropic factors (choline, methionine, folic acid and vitamin B-12) were studied in a 2 X 2 factorial experiment. Both increased lipid and lipotrope deletion resulted in decreased growth in rats, but only increased lipid caused growth depression in woodchucks. Lipotrope depletion resulted in elevated serum markers of hepatic injury and hepatic lipid accumulation in rats but not in woodchucks. Hematological changes induced by the low lipotrope diets included decreased packed cell volume, total hemoglobin and mean corpuscular volume (MCV) in rats but increased MCV in woodchucks. The woodchuck appears to be more resistant than the rat to induction of hepatic injury by lipotrope deficiency.