THE DEVELOPMENT OF DIGESTIVE CAPACITY IN YOUNG PIGS: EFFECTS OF AGE AND WEANING SYSTEM z'2

Two experiments with 49 crossbred pigs were conducted to examine the effects of age and weaning system on various indicators of digestive development and capacity. In Exp. 1, pigs reared exclusively by the sow with no access to creep feed were killed at 1, 8, 16 and 22 d of age. Other pigs, weaned at 16 d of age to a milk protein diet fed either in dry or liquid form, were killed at 22 d of age. In Exp. 2, pigs were reared exclusively by the sow and killed at 14, 17 and 21 d of age. All data are expressed as units per kilogram body weight. The pH of stomach contents increased during the first week of age. Stomach pH was higher in weaned pigs than in sow-reared pigs at 22 d of age. Sow-reared pigs showed little change with age in amount of stomach contents. Intestinal length tended to decrease with age. Intestinal weight per unit length increased with age and was higher in weaned pigs. Weaned pigs had a larger pancreas than pigs reared by the sow. In Exp. 1, proteolytic activity of stomach contents decreased with age until 22 d when an increase in activity occurred. The activity in weaned pigs was greater than that in sow-reared pigs. Intestinal trypsin activity increased at 22 d of age and was higher in weaned pigs. Intrapancreatic trypsin activity increased from 1 to 8 d of age, after which there was little change. Less activity was found in the pancreas