Effect of Fat in the Diet of Rats on Their Growth and Their Excretion of Amino Acids

Abstract

Rats fed ad libitum a diet with no added fat and supplemented with ethyl linoleate gained 29% less than rats fed diets containing 8% of corn oil or lard. There was no significant difference in the gains of rats when the intakes of protein and energy were equalized. The fecal excretion of phenyalanine, valine, lysine and methionine was from two to 5 times greater than the excretion by the renal pathway. The fecal excretions of the 4 amino acids were less by the rats receiving corn oil in their diet than by rats receiving a diet with no added fat. The differences were statistically significant for valine, lysine and methionine. The urinary excretion of valine and methionine was significantly less by the rats fed the diet containing corn oil than by the rats fed a diet containing no added fat. Mature rats that had been fed a depletion diet until they had lost approximately one-third of their weight were fed on a regimen providing equalized intakes of protein and energy. One group was fed a diet containing 8% of fat and the other group a diet with no added fat. The results, on the basis of growth and excretion of amino acids, favored the diet containing corn oil. The differences, however, were small and not statistically significant.