Effects of Lactobacillus Reuteri LR1 on the Growth Performance, Intestinal Morphology and Intestinal Barrier Function in Weaned Piglets

The objective of this study was to investigate the effects of Lactobacillus reuteri LR1 (LR1), a new strain isolated from the feces of weaning piglets, on the growth performance, intestinal morphology, immune response and intestinal barrier function in weaned piglets. A total of 144 weaned piglets (Duroc×Landrace×Yorkshire, 21 d of age) with an initial BW of 6.49±0.02 kg were randomly assigned to 3 dietary treatments to give 8 pens per treatment and 6 piglets per pen. Piglets were fed with a basal diet (control group), a basal diet supplemented with 75 mg/kg aureomycin +100 mg/kg olaquindox (antibiotic group) or a basal diet supplemented with 5×10¹⁰ CFU/kg LR1 (LR1 group) for a 14-d period. At the end of study, the ADG, ADFI and G:F were calculated, and 8 randomly selected piglets from each treatment were euthanized for collecting samples. We found that LR1 treatment increased ADG (22.73%, P<0.05) compared with the control group. However, no significant differences were observed in ADFI, ADG and G:F between the LR1 group and the antibiotic group. LR1 treatment decreased (P<0.05) serum IL-6 concentration but increased (P<0.05) IL-22 and TGF-β content in the mucosa of the ileum compared with the control and antibiotic treatment. We found LR1 treatment increased (P<0.05) villus height of the ileum and reduced (P<0.05) crypt depth of the jejunum, and increased (P<0.05) the ratio of villus height/crypt depth in the jejunum and the ileum compared with the control and antibiotic treatment. Compared with control, LR1 increased (P<0.05) the mRNA expression of the antimicrobial peptide pBD2 and PG1-5 in the mucosa of the ileum, whereas antibiotic treatment decreased (P<0.05) expression. Additionally, we demonstrated that LR1 treatment increased (P<0.05) toll-like receptor (TLR)-2 expression but decreased (P<0.05) the TLR-4 expression in the mucosa of the ileum compared with the control group. Furthermore, compared with the control and antibiotic treatment, LR1 treatment increased (P<0.05) the mRNA expression of tight junction protein ZO-1 and claudin-1 in the mucosa of jejunum, and also increased (P<0.05) the mRNA expression of ZO-1 and occludin in the mucosa of ileum. In conclusion, these data suggest that dietary LR1 supplementation at 5×10¹⁰ CFU/kg could improve the growth performance, intestinal morphology and intestinal barrier function in weaned piglets.