MODE OF CHOLESTEROL INGESTION AND ATHEROSCLEROSIS IN THE YOUNG BOVINE

SUMMARY Varying degrees of atherosclerosis were noted in aortas and coronary arteries of calves fed high-cholesterol diets for 25 weeks. Intimal lipid was more extensive in aortas and circumflex coronary arteries from nonruminating calves fed cholesterol in a highfat, liquid (milk) diet than in arteries from ruminating calves fed cholesterol in low-fat (grain) diet. Cholesterol deposition was coextensive with the intimal lipid. Plasma and liver cholesterol levels were higher in calves fed cholesterol in the high-fat, liquid diet but variation in animal response was substantial. Digestibility data indicated that the low amount of fat in the diet of the calves receiving primarily grain depressed absorption of cholesterol. Moreover, exposure of cholesterol to digesta of the ruminoreticulum, as would occur in grain feeding, was shown by in vitro and in vivo observations to enhance degradation of cholesterol.