Early inoculation of a multi-species probiotic to piglets – impact on gut microbiome and immune responses

Abstract

Background: Intestinal diseases in nursery pigs cause poor performance and health as well as constitute a risk for development of antimicrobial resistance. Research points towards early life serving as a period of physiological plasticity rendering interventive strategies, why the objective of this study was to assess the effect of early inoculation of a probiotic multi-species product to newborn piglets on their ability to overcome weaning and the intestinal challenges that follows. The probiotic product consisted of Lactobacillus rhamnosus, Enterococcus faecium, Bifidobacterium longum subsp. infantis and Bifidobacterium breve and was orally administered to the newborn piglets daily until day 4, subsequently every 2nd day until weaning on day 28 (4x10⁹ CFU/dose). The Control group was administered a placebo mixture. Results: Alpha diversity indices showed that the Probiotic pigs had a lower diversity index in feces on day 7, whereas the Shannon diversity was higher in feces on day 28 and in intestinal content on day 23. Nested PERMANOVA on Bray-Curtis distance metrics analysis demonstrated alterations in microbial diversity in intestinal content and tissue as well as in feces between the two treatment groups on day 35 after cessation of probiotic administration. Most zOTUs found to significantly differentiate the two treatment groups were found pre-weaning. Bifidobacterium breve, Lactobacillus salivarius as well as Clostridium ramosum stood out by being significantly more abundant in feces of Probiotic pigs more than once. The Probiotic pigs had a higher expression of MUC2, IL-8, and IL-17 post-weaning, whereas the acute phase protein SAA was downregulated. Incidence of diarrhea during the first week after weaning was lower in the Probiotic group. Furthermore, Probiotic pigs had a lower concentration of cadaverine in intestinal content as well as a lower percentwise increase in white blood cells from pre- to post-weaning. Conclusions: In conclusion, early probiotic inoculation may drive a long-term immunomodulation through changes in specific microbial antigens, leading to higher resilience during challenging situations such as weaning. An interesting finding was that the effect of the early probiotic inoculation was observed after weaning and cessation of the probiotic product.