Evaluation of bacterial diversity in the gut of piglets supplemented with probiotics using ribosomal intergenic spacer analysis

Abstract

In this study, ribosomal intergenic spacer analysis (RISA) was used to monitor changes of intestinal microbiota of piglets treated at birth with or without Pediococcus acidilactici (PA) and/or Saccharomyces cerevisiae ssp. boulardii (SCB) and weaned piglets fed with control diet supplemented with PA and/or SCB or antibiotic. During lactation, probiotics were given orally to piglets three times a week. At weaning (day 21), probiotics and the antibiotic, tiamulin, were added to the diet. Fifteen piglets per treatment were slaughtered at day 18 and day 24. The tracking of each probiotic from colonic samples was done using PCR primers specific for PA targeting the 16S rRNA gene or a specific culture medium for enumeration of SCB. The results showed the presence of probiotics in colonic samples of piglets supplemented with probiotics. Dendograms (UPGMA and Ward’s method), and non-metric multidimensional scaling analysis showed that the variability of RISA profiles in colonic microflora between individual piglets within a treatment was too high to obtain a grouping based on probiotic supplementation. Based on the relative frequency of internal transcribed spacers from RISA profiles (indicator species analysis) and diversity indices (Shannon, richness and evenness), both PA and the antibiotic treatments reduced the bacterial diversity in the gut of piglets after weaning compared with preweaning, while diversity was slightly increased postweaning compared with preweaning in control without antibiotic and SCB groups. In conclusion, all dietary additives differently affected postweaning microbial community composition; however, both antibiotic and PA reduced postweaning microbial diversity suggesting a possible benefit of PA supplementation during the postweaning transition period. Key words: Intestinal flora, piglet, PCR, probiotic, RISA profile, weaning