138 Effects of Diet Complexity and L-Threonine Supplementation on Immune Response and Intestinal Barrier Function in Nursery Pigs

Abstract

Abstract The aim was to investigate the effects of diet complexity and L-Thr supplementation on immune response and intestinal barrier function in nursery pigs. Thirty-two pigs (7.23 ± 0.48 kg of body weight) were randomly assigned dietary treatments in a 2 × 2 factorial arrangement based on diet complexity (complex or simple) and L-Thr supplementation (standard, NRC 2012 or 15% more). The complex diet contained fish meal, plasma protein and dried whey to mimic a conventional nursery diet. The simple diet was formulated with corn, wheat, and soybean meal and did not contain any animal products. Pigs were individually housed and fed experimental diets ad libitum for 14 d. All data were analyzed using mixed procedure of SAS with the individual pen as the experimental unit. Pigs fed the simple diet had greater (P < 0.05) plasma interleukin (IL)-6 and IL-10 concentrations compared to those fed the complex diet. Pigs fed the simple diet tended to show greater (P < 0.10) expression of genes encoding for tumor necrosis factor-α, claudin-1, and zonula occludens-1 in the jejunum compared to those fed the complex diet. The addition of L-Thr increased (P < 0.05) villus height and numbers of both villi and crypt goblet cells in the jejunum and deepened (P < 0.05) crypts in the proximal colon. Also, L-Thr-supplemented diets upregulated (P < 0.05) the expression of the gene encoding for occludin and tended to downregulate (P < 0.10) IL-6 gene expression in the jejunum. Trends (P < 0.10) for interaction between diet complexity and L-Thr supplementation were observed in villus height:crypt depth ratio, the number of goblet cells, and IL-6 gene expression in the jejunum. In conclusion, feeding a simple diet stimulated the immune system of nursery pigs compared to a complex diet. Dietary L-Thr supplementation fortified intestinal structure and function.