The development of digestive capacity in young pigs: effects of weaning regimen and dietary treatment.

In Exp. 1, 24 crossbred pigs were weaned at 21 d of age to either a 24% milk protein diet or a 24% soy protein diet, both of which were fed hourly in liquid form. In Exp. 2, 45 crossbred pigs were weaned at 21 d of age to either a 24% milk protein diet fed hourly in liquid form, the same diet fed ad libitum in dry form or a 24% protein, corn-soybean meal diet fed ad libitum in dry form. Pigs were killed at 7 or 14 d postweaning in Exp. 1 and 7, 14 or 21 d postweaning in Exp. 2. In both experiments, pigs fed milk based diets had faster weight gains and more efficient feed conversion ratios than pigs fed diets containing soy protein. All data are expressed as units per kilogram body weight. Pigs fed a soy protein diet tended to have a greater intestinal length than pigs fed milk protein diets. Growth of the pancreas in relation to body weight was greater in pigs fed diets containing soy protein than in pigs fed milk protein. Pigs fed a soy protein diet tended to have greater trypsin and chymotrypsin activities in the intestinal contents and lower activities in the pancreas than did pigs fed milk-based diets. These results suggest that soy-containing diets caused a greater secretion of trypsin ad chymotrypsin into the intestine than did milk-containing diets.