Effects of Saccharomyces cerevisiae var. boulardii on growth, incidence of diarrhea, serum immunoglobulins, and rectal microbiota of suckling dairy calves

The present study was carried out to elucidate the growth, incidence of diarrhea, serum immunoglobulins, and rectal microbiota of dairy calves as they were supplemented with live Saccharomyces cerevisiae var. boulardii (S. cerevisiae var. boulardii). A total of 48 newborn Holstein dairy calves were selected as experimental animal. The calves were divided into four experimental groups based on the concentration of S. cerevisiae var. boulardii as feed supplement. The rate of feed supplement for the four groups were 0, 1, 3, and 5 g/day/calf of live S. cerevisiae var. boulardii, respectively. All animals of 0 were considered as control group. The study was continued for 42 days. Samples of blood and rectal contents were collected on d 21 and 42. The results showed that supplementation of S. cerevisiae var. boulardii improved the body weight, average daily gain, total feed intake, and feed conversion ratio during the first 21 d of life (P<0.05) of the experimental calves. Serum concentration of IgA, IgM, and IgG increased by 3 g/day and 5 g/day of treatments during the first 21 d of life (P<0.05). Moreover, supplementation with S. cerevisiae var. boulardii increased fecal score (3 and 5 g/day groups) and reduced the incidence of diarrhea (1, 3, and 5 g/day groups) during the first 21 d after birth (P<0.05). Both on d 21 and 42 of life, rectal samples were predominated by Firmicutes, Bacteroidetes, Fusobacteria, Proteobacteria, and Actinobacteria. Additionally, dietary supplementation with S. cerevisiae var. boulardii increased the relative abundance of genera Lactobacillus, Paracoccus, Blautia, and Eubacterium_oxidoreducens_group. However, compared to control, the relative abundance of Fusobacterium on d 21, was reduced (P<0.05). These findings indicated S. cerevisiae var. boulardii supplementation reduced the incidence of diarrhea, while improving serum immunoglobulins concentrations and modulating rectal microbiota in young dairy calves. Furthermore, we recommend that 3 g/day/calf S. cerevisiae var. boulardii supplemented feed be administered to dairy calves during their first 21 d of life.