Effect of a multispecies lactobacillus formulation as a feeding supplement on the performance and immune function of piglets

Lactobacilli are essential members of the swine intestinal microbiota, with proposed health promoting effects. There is a reduction in the abundance of intestinal lactobacilli around weaning; this has been considered to predispose piglets to gut disturbances, e.g. diarrhea. Therefore, dietary supplementation with lactobacilli may help in maintaining better host health around weaning. In this study, we assessed the efficacy of a bacterial supplement containing six strains of the genus Lactobacillus in a feeding trial conducted in recently weaned pigs. Twenty piglets were divided into two groups (n=10) based on litter origin. Piglets in the supplementation group were fed the lactobacilli mixture (total cell count 1×1010) daily for three weeks, while those in the control group were provided with a probiotic-free placebo. The aim of this study was to evaluate the intestinal survivability of the feeding strains, as well as the effects of the supplementation on the performance of the piglets. Furthermore, the expression of selected cytokines was analyzed in the gut mucosa. The main effect of the lactobacilli supplementation observed was immunomodulation in the piglet intestine, especially in the large intestine. Upregulated expressions of IL-4 and IFN-α were detected in the cecum, with downregulated expressions of IL-8 and TNF in the colon of the supplementation group. In addition, supplementation downregulated the expression of TGF-β1 in the jejunum, ileum and colon. An increased total bacterial number was detected in the jejunum of the supplementation group, but no change in the intestinal digesta pH or in the numbers of lactobacilli was induced by the supplementation. In addition, the strains which had been supplied could not be isolated from feces, indicating that they had been unable to colonize the piglet intestine in significant numbers. The lactobacilli supplementation had no effect on the weight gain or the intestinal mucosal morphology of the piglets. While the lactobacilli supplement used in this study failed to achieve a growth-enhancing effect, and the supplemented strains appeared to have a limited ability to compete with the indigenous intestinal microbiota of piglets, the supplement evoked immunomodulatory properties in the piglet intestine.