EFFECTS OF HIGH-CALCIUM INTAKE ON FAT DIGESTION AND BILE-ACID EXCRETION IN FECES OF VEAL CALVES

We tested the hypothesis that apparent digestibility of fat by veal ca lves is determined by the participation of bile acids in the process o f fat absorption and is, therefore, negatively associated with bile ac id excretion in feces. Veal calves were fed milk replacers that contai ned whey protein and either a low (5.2 g of calcium/kg of air-dried di et) or high (12.4 g of calcium/kg of air-dried diet) concentration of calcium. The high calcium milk replacer contained extra calcium in the form of calcium formate. Final body weight was not significantly infl uenced by diet after the milk replacers had been fed for 27 wk. Feces were quantitatively collected during wk 23 of the trial. The high calc ium milk replacer reduced apparent fat digestibility by 5.6 percentage units and increased bile acid excretion in feces by 90% compared with the low calcium milk replacer. The extra calcium intake decreased app arent absorption of magnesium and phosphorus. We proposed that a high intake of calcium by veal calves would increase the amount of insolubl e calcium, magnesium, and phosphate complexes in the intestinal lumen, which, because of the binding of bile acids, would exclude bile acids from the process of fat digestion and inhibit reabsorption of bile ac ids. As a result, fat digestion is impaired, and bile acid excretion i n feces is enhanced. The complex formation in the ileal lumen also exp lains why high calcium intake reduces magnesium and phosphorus absorpt ion in veal calves.