Effects of intrauterine growth retardation and Bacillus subtilis PB6 supplementation on growth performance, intestinal development and immune function of piglets during the suckling period

The aim of this study was to investigate the effects of intrauterine growth retardation (IUGR) and Bacillus subtilis PB6 supplementation in formula milk (FORM) on growth performance, intestinal development and immune function of neonates using a porcine model. Fourteen pairs of normal birth weight and IUGR piglets (7 days old) were randomly assigned to receive FORM or FORM supplemented with B. subtilis PB6 (FORM-BsPB6) for a period of 21 days. Blood samples, intestinal tissues and digesta were collected at necropsy and analysed for morphology, digestive enzyme activities, immune cell abundance, expression of genes associated with innate immunity and barrier function and microbial populations. Regardless of diet, IUGR significantly decreased average daily dry matter intake and average daily weight gain (P < 0.05). Moreover, IUGR significantly decreased plasma concentrations of immunoglobulin A, interleukin 1 beta, count and percentage of blood lymphocytes (P < 0.05). Meanwhile, IUGR markedly decreased villous height and maltase activity, as well as mRNA abundance of Toll-like receptor 9 and Toll-interacting protein in the ileum (P < 0.05). Regardless of body weight, FORM-BsPB6 markedly decreased the feed conversion ratio (P < 0.05), due to better intestinal development, as indicated by increased villous height (P < 0.05), activities of maltase and sucrase in the intestine (P < 0.10). Moreover, both mRNA and protein abundances of zonula occludens-1 and claudin-1 in the ileum as well as the copy number of Bacillus in colonic digesta were increased (P < 0.05) in piglets fed FORM-BsPB6 relative to FORM. The results of this study indicate that IUGR delayed growth, intestinal development and immune function of piglets, while FORM-BsPB6 improved digestive capability and intestinal barrier function.