Effects of Age and Weaning on Enzyme Activities of Abomasum and Pancreas of the Lamb

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Abstract
The effect of age and weaning on enzyme activities of the abomasum and pancreas of the lamb was studied. Sixty-nine lambs were maintained at the preruminant stage until 42 days of age or weaned between 20-30 days. They were slaughtered between birth and 100 days, and the mucosa of their abomasum and their pancreas were collected. At 2 days of age there was a threshold of glandular growth and of development of enzyme secretory potentialities. The pancreas showed an extensive hyperplasia without growth until day 2; its weight increased after day 7 but only by hypertrophy. Quantities of gastric enzymes in relation to empty live weight increased between birth and 2 days, but that of chymosin then decreased, whereas pepsin did not change significantly; the effects of weaning were similar. The evolution of pancreatic enzyme activity was usually the reverse of that of chymosin; however, trypsin activity was low at birth and that of colipase did not increase at weaning. The ratio of colipase to lipase was always higher than 1, showing that lipase always was saturated in the lamb. The pancreas seemed to take over the secretion of abomasal proteolytic enzymes. Potentialities of enzyme digestion appeared to be influenced mainly by the age or weight of the animal, these potentialities were minimal for at least several days during the 1st neonatal week and, if there was enzymatic adaptation to the amounts of the ingested substrate, it did not occur rapidly.

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