Enzyme potentialities of the abomasum and pancreas of the calf. II. Effects of weaning and feeding a liquid supplement to ruminant animals.

Thirty-nine male Friesian calves, divided into three groups (L, S and SL), were reared until they were 147 to 175 days old. Group L calves remained preruminant until slaughter. Group S calves were weaned between 5 and 9 weeks of age and then received a concentrate feed and dehydrated fescue ad libitum. Besides this diet, group SL calves received a liquid supplement containing whey powder and soyabean oil meal, supplying a total of 940 g of dry matter and 5,060 g of water per day. The slaughter age of the calves in each group was chosen so that carcass weight in the three groups was similar. At slaughter, the abomasum and pancreas of each animal were collected and the gastric (chymosin and pepsin) and pancreatic (chymotrypsin, trypsin, lipase and amylase) enzymes were assayed. Weaning caused a decrease in the chymosin content and an increase in the pepsin content of the abomasum. The amount of chymosin per kg of carcass was on the average 2.8-fold lower and that of pepsin 1.9-fold higher in groups S and SL than in group L. The amount of pepsin tended to be higher in group S than in group SL, but only the difference observed (36%) for the total amount was significant. In group S, the pancreata showed more chymotrypsin, trypsin and amylase activities but less lipase activity than in group L; the observed differences in these activities per kg of carcass were 32, 49, 70 and 24%, respectively. The activities of group SL were lower than those of group L for trypsin, chymotrypsin and lipase but higher for amylase (17, 12, 44 and 18%, respectively). Group SL exhibited lower activities than group S (55, 67, 16 and 44%, respectively, for trypsin, chymotrypsin, lipase and amylase). Weaning appeared to induce large changes in abomasal and pancreatic enzyme potentialities which exhibited patterns similar to the variations in the amounts of substrate intake. In our experimental conditions, giving a liquid supplement to ruminant calves had a depressive effect on the activities of the enzymes (except chymosin), in the pancreas and the abomasum.