The Effect of Dietary Cholesterol, Energy Intake, and Oxygen Consumption on Cholesterol Metabolism in the Chick

Abstract

This experiment, involving 320 chicks, was conducted to determine the effects of dietary cholesterol, restricted caloric intake, and genetic lines on cholesterol metabolism in the bird. The two lines of chicks studied had been divergently selected for oxygen consumption and had been shown to differ significantly (P<.01) in weight gain and carcass lipid deposition. The dietary treatments, administered for a 2-week period, consisted of two levels of dietary cholesterol (none and supplemented) for each of two levels of energy (ad libitum and restricted). At the end of this 2-week period, the birds were injected intravenously with l-14C-acetate and their livers removed 4 hr later. Hepatic cholesterol and lipid synthesis were measured by the uptake of acetate.Added dietary cholesterol significantly (P<.01) decreased hepatic cholesterol synthesis, lipid synthesis, and specific activity of hepatic cholesterol but increased plasma and liver cholesterol. However, the elevation in plasma and liver cholesterol represented only .9 and 1.8% respectively, of the increase in total intake of dietary cholesterol. Metabolizable energy of diets fed ad libitum was also significantly (P<.01) reduced with supplemented dietary cholesterol. A significant (P<.01) difference in body weight was present between the two lines, with low oxygen consuming (LOC) birds exhibiting heavier body weights than high oxygen consuming (HOC) birds. A significant interaction between line and energy intake (P<.05) was present for hepatic cholesterol levels; LOC birds exhibited higher levels of hepatic cholesterol than HOC birds when both groups were fed at restricted levels. Energy restriction significantly (P<.01) reduced weight gain and carcass fat. The results showed that of the three variables analyzed, dietary cholesterol had the most effect on altering cholesterol metabolism.