Abstract: 【Objective】 The purpose of this experiment was to investigate the effects of Lactobacillus reuteri I5007 on intestinal villi maturation and intestinal barrier function in newborn piglets. 【Method】 Nine litters of 1-day-old Duroc×Landrace×Yorkshire newborn piglets and eight healthy piglets with similar body weight in each litter were selected. Piglets were randomly divided into three groups with three litters per group. The three groups were control group (oral administrated with 0.1% sterile peptone solution), the first 4 days dosed group (1-4 d, daily orally administrated with 1.2×10¹⁰ CFU of L. reuteri I5007 per piglet), and the every 4-day dosed group (1, 5, 9, 13, 17, and 21 d, daily orally administrated with 1.2×10¹⁰ CFU of L. reuteri I5007 per piglet). The trial was conducted for 21 d. During the trial, each litter of piglets were fed by a sow, respectively. Four healthy piglets closest to the average body weight from each group were fasting weighted, anesthetized and then slaughtered on d 7, 14 and 21. The small intestine was carefully dissected from the mesentery and segments (the same location in all piglets), including duodenum, jejunum and ileum, were collected. Growth performance, intestinal morphology, disaccharidase activity and expression of tight junction (TJ) proteins were measured. 【Result】 Oral administration with L. reuteri I5007 had no significant effect (P＞0.05) on growth performance, but had impacts on piglet intestinal morphology at different time points. On d 7, duodenal villus height, villus height/crypt depth and goblet cells density and ileal goblet cells density of piglets in every 4-day dosed group were increased significantly (P＜0.05) compared with those of control piglets. Piglets in first 4 days dosed group had distinct higher (P＜0.05) duodenal villus height/crypt depth and goblet cells density and ileal goblet cells density than control piglets, but not villus height/crypt depth (P＞0.05). On d 14, administration with L. reuteri I5007 in every 4-day dosed group robustly increased (P＜0.05) duodenal villus height/crypt depth and ileal goblet cells density. Ileal goblet cells density of piglets in first 4 days dosed group was significant higher (P＜0.05) than that of control piglets, but lower (P＜0.05) than that of piglets in every 4-day dosed group. On d 21, piglets of every 4-day dosed group had an increased goblet cells density (P＜0.05) in both duodenum and ileum. Compared with control group, administration of L. reuteri I5007 in first 4 days dosed group also augmented (P＜0.05) ileal goblet cells density, but reduced (P＜0.05) duodenal villus height/crypt depth. In addition, piglets in first 4 days dosed group had lower (P＜0.05) duodenal villus height/crypt depth and goblet cells density than those of piglets in every 4-day dosed group. For disaccharidase activity, piglets in every 4-day dosed group had higher (P＜0.05) both sucrase and maltase activities in jejunum than those of control piglets. Only jejunal maltase activity of first 4 days dosed piglets was enhanced (P＜0.05) compared with control piglets, while jejunal sucrase and maltase activities were significantly lower (P＜0.05) than those of every 4-day dosed. Furthermore, piglets in every 4-day dosed group had significant higher expression of Claudin-1, Occludin and ZO-1 in both jejunal and ileal epithelial cells (P＜0.05). Administration of L. reuteri I5007 in first 4 days dosed group also promoted (P＜0.05) expression of jejunum epithelial Claudin-1 and ZO-1 and ileum epithelial Claudin-1. However, the level of jejunum epithelial Occludin of first 4 days dosed piglets was obviously lower (P＜0.05) than that of every 4-day dosed piglets. Besides, the levels of Claudin-1 (P = 0.1) and ZO-1 (P = 0.1) in ileum epithelium of first 4 days dosed piglets had a trend of decrease compared with every 4-day dosed piglets. 【Conclusion】 Every 4-day administration of L. reuteri I5007 in newborn piglets can promote the maturation of intestinal villi, improve jejunal disaccharidase activity, and increase expression of TJ protein of intestinal epithelial cells. Thus, L. reuteri I5007 may play a role in protecting or augmenting intestinal barrier function in newborn piglets.

Key words: lactobacillus, nwborn piglets, intestinal morphology, disaccharidase, tight junction, intestinal barrier