Effect of dietary zinc supplementation on Escherichia coli septicemia in weaned pigs

Objective: To determine the effect of 3000 ppm dietary zinc oxide (ZnO) on bacterial counts in the mesenteric lymph nodes and systemic circulation. Methods: Eighteen piglets were fed a commercial starter diet with (ZnO treatment) or without (controls) supplementation of 3000 ppm zinc oxide. After a 6-day adaptation to the diets, the pigs were intramuscularly injected with lipopolysaccharide (LPS) (derived from E. coli 026:B6) at 150 mu g per kg bodyweight. The pigs were monitored throughout the experimental period. Twenty-four hours after LPS injection, pigs were euthanized and samples were collected. Results: Bacteria could be cultured from ileal mesenteric lymph nodes in fewer ZnO-treated (three of nine) than control (eight of nine) piglets (P<.05). In ZnO-treated pigs, there tended to be fewer colony forming units (CFU) of bacteria per g of tissue from the ileal mesenteric lymph nodes than in the pigs fed the control diet (P<.1). Treatment had no effect on the species of bacteria cultured. Treatment had no effect on bacteremia, Implications: Supplementing starter diets with 3000 ppm ZnO reduced the level of bacterial translocation from the small intestine to the ileal mesenteric lymph node. However, the mechanism whereby this effect was achieved could not be determined.