Effect of dietary copper on intestinal mucosa enzyme activity, morphology, and turnover rates in weanling pigs

Twenty-four pigs from four litters weaned at 21 d of age (6.6 kg of BW) were used to evaluate the influence of 250 ppm of dietary Cu on intestinal mucosa glucose-6-phosphatase (GP), alkaline phosphatase (AP), and adenosine triphosphatase (ATPase) activity; mucosal morphology; and the turnover rate of the intestinal mucosa throughout the gastrointestinal tract. Pigs were allotted into four pens of six pigs each based on sex, litter, and weight. Pens were then assigned to one of two treatments: 1) corn-soybean meal-whey diet with no antimicrobials (CO), or 2) CO + 250 ppm of Cu. Pigs were fed twice daily an amount approximately equal to ad libitum intake for 14 d. On d 14, pigs were injected i.p. with [3H]thymidine (50 mCi/kg of BW) 10 h after the morning meal. One pig from each pen was euthanatized at 1, 6, 12, 20, 32, and 44 h postinjection, and intestinal tissue was collected from the duodenum, two jejunum sites (upper and lower), ileum, cecum, and colon. The activity of GP and AP in the lower jejunum tended to decrease in pigs fed CU (P < 0.11, P < 0.08, respectively). The ATPase activity was not affected by treatment (P > 0.10). Crypt death, villus height, or epithelial cell size (P > 0.10) were not affected by feeding Cu. Migration rate of epithelial cells up the villus was also not affected by treatment (P < 0.10; P < 0.05, respectively) and the lower jejunal cell generation interval was longer (P < 0.05) in pigs fed the Cu diet. From these data we conclude that the addition of 250 ppm of Cu to the diet of weanling pigs slows the turnover rate of the jejunal intestinal mucosa, which may result in a lower energy requirement for the maintenance of this tissue.