Influences of dietary starch structure on intestinal morphology, barrier functions, and epithelium apoptosis in weaned pigs

The objective of the present study was to evaluate the effects of dietary starch structure (amylose/amylopectin ratio, AR) on intestinal health of weaned pigs by determining the intestinal morphology, barrier functions, epithelium apoptosis and digestive enzymes. A total of one hundred and eight pigs (initial body weight 7.51 +/- 0.05 kg) were randomly allotted on the basis of their body weight (BW) and litters to one of the six experimental diet treatments with six replicates per treatment and three pigs per replicate. The six diets included a control (corn-soybean meal basal diet, CON) diet and five experimental diets with AR being 2.90, 1.46, 0.68, 0.31 and 0.14, respectively. The diets and water were provided ad libitum for 21 d. Results showed that pigs fed CON and AR 2.90 diets had higher (P < 0.05) villus height and ratio of villus height : crypt depth in the jejunum and ileum compared with the other four starch groups. Pigs of CON and AR 0.14 groups had greater (P < 0.05) activities of sucrase (SA) and maltase (MA) than the pigs of other groups. Additionally, compared with the high amylopectin (AR 0.31 and 0.14) groups, the total apoptotic percentage was significantly decreased in (P < 0.01) CON and high amylose (AR 2.90) groups. Ingestion of CON and high amylose diets upregulated (P < 0.05) the levels of B-cell lymphoma-2 (Bcl-2) and occludin (OCLN) gene expression in duodenum and jejunum. However, no significant differences in the level of zonula occludens 1 (ZO-1) gene expression were observed in pigs fed with different AR diets. Interestingly, CON and high amylose groups enhanced the localization of ZO-1 protein in apical intercellular region of jejunal epithelium. Together, these results suggest that diets with high amylose can influence the intestinal health of young pigs by improving their intestinal barrier functions and reducing the epithelial cell apoptosis.