A placebo-controlled study of the effects of Saccharomyces cerevisiae var. boulardii CNCM I-1079 probiotic on faecal quality, microbiota and immunity in weaned kittens

Acute diarrhoea or soft stools can occur in young kittens in response to environmental stress. This study investigated the effect of probiotic supplementation on gastrointestinal health and immunological parameters in kittens exposed to three environmental or nutritional events. Healthy weaned 10-week-old kittens were assigned to a daily dietary supplement of Saccharomyces cerevisiae var. boulardii CNCM I-1079 (S. boulardii) or placebo for 7 weeks (20 kittens/group). The study events were a routine booster vaccination (Week 3), a change in housing (Week 5), and a diet transition (Week 6). Outcomes included faecal scores and percentage dry matter (DM%), total serum IgG, faecal IgA, and faecal microbiota composition. Statistical analyses included Linear Mixed Models and Generalized Linear Mixed Models with Group, Time and Group x Time interaction as fixed effects; longitudinal Kruskal-Wallis test corrected for false discovery rate was used for microbial outcomes. Results. A higher proportion of kittens in the probiotic vs placebo group maintained optimal faecal scores throughout the whole study (12/20 vs 8/20). There was no group x time interaction for faecal quality, but in Week 5, mean faecal score was lower (firmer stools) (P = 0.007) and DM% was lower (P = 0.032) in the probiotic vs placebo group. At Week 7, serum IgG was higher in the probiotic vs placebo group (P <0.039), having increased 250% vs 62% respectively between Week 0 and Week 7. Faecal IgA concentration tended to be higher in the probiotic vs placebo group after booster vaccination (P = 0.068). A decrease in the Shannon alpha diversity of faecal microbiota post diet transition was significant in the placebo group only (P = 0.005). Microbiota composition (weighted Unifrac beta diversity) differed between groups overall (P = 0.025) and at Week 4 (P = 0.0174).