Impact of different feed intake levels on intestinal morphology and epithelial cell differentiation in piglets

Abstract This study aimed to investigate the effect of feed intake levels on the development of intestinal morphology and epithelial cell differentiation in piglets. Sixty-four 35-day-old healthy weaned piglets ([Large White × Landrace] × Duroc) with an initial weight (6.93 ± 0.12 kg) were randomly divided into four groups (100%, 80%, 40%, and 20% feed intake) with eight replicates of two pigs each. Samples were collected on days 3 and 7. The results revealed that with an increase in feed restriction degree and time, the body weight and organ index of piglets significantly decreased, and the villus height and crypt depth of the duodenum, jejunum, and ileum also decreased linearly (P < 0.05). After three days of feed restriction, jejunal ki67, endocrine cells, goblet cells, and villus endocrine/villus height all decreased linearly, but the villus cup/villus height ratio increased linearly, and the 40% and 20% were significantly higher than those of the 100% and 80% (P < 0.05). There was also a linear decrease in jejunal ki67, endocrine cells, goblet cells, and villous endocrine/villus height in piglets fed 7 days of food restriction; however, the villus goblet cells/villus height ratio in the 20% was significantly higher than that in the 40% group and was not different from that in the 80% (P < 0.05). During three days of feed restriction, the expression of jejunal differentiation marker genes showed a linear decreasing trend (P < 0.05), but increased linearly after seven days of feed restriction. The expression levels of interleukin17 (IL-17) and IL-22 also increased linearly (P < 0.05). KEGG and GSEA analyses indicated that the PPAR signaling pathway, ECM-receptor interaction, and Th1, Th2, and Th17 cell differentiation were significantly enriched in these processes. RT-QPCR demonstrated that both PPAR and ECM-receptor interactions were significantly activated during seven days of feeding restriction (P < 0.05). The results showed that with an increase in feed restriction intensity and time, the intestinal morphology and epithelial cell proliferation and differentiation were significantly reduced, except for the goblet cells. This phenomenon is related to the regulation of intestinal differentiation by IL-17 and IL-22 secreted by the Th cells.