Effects of a Diet Containing 40% Dried Whey on the Performance and Lactase Activities in the Small Intestine and Cecum of Hampshire and Chester White Pigs 1

Two 21-day feeding trials were conducted using either 24 Hampshire (H) or 24 Chester White (CW) pigs at approximately 5 months of age to evaluate the effects of a diet containing 40% dried whey on the performance and the lactase activities in the gut of finishing pigs. Dried whey increased the incidence and severity of diarrhea in both CW and H (P<.005) but depressed the rate of gain, gain/feed, and feed intake (P<.005) only in H. The pigs were slaughtered on day 19, following a 12-hr fast (0 hr), or at 1, 2 or 3 hr after consuming approximately 150 g of lactose from 500 g of the dried whey diet. Previous dietary treatment did not affect the rate at which lactose left the stomach or the recovery of lactose in the small intestine except for a diet • segment interaction (P<.05) in H where more lactose was recovered in the lower one-third of the intestine of the controls. Total mucosal and contents lactase activities in the small intestine were not altered by diet but total cecal lactase was increased (P<.05 H; P<.005 CW) in the groups fed dried whey. Times after feeding did not affect lactase activities in CW but in H the 0 hr group had lower (P<.005) total mucosal activity than the 1-, 2-, or 3-hr groups. The lactase activity in the contents of the intestine of H fed dried whey was greater (P<.05) than that of the controls. (