The Effects of Dietary Saccharomyces cerevisiae Supplementation on Gut Microbiota Composition and Gut Health in Aged Labrador Retrievers.

The intestinal microbiome changes with age, influencing the host's health and immune status. Saccharomyces cerevisiae ( S. cerevisiae ) positively affects intestinal function in humans and animals, but its effects on gut health and the microbiota profile in aged dogs have not been thoroughly investigated. Twenty aged Labrador Retrievers were divided into two groups: a control group (CON) and a S. cerevisiae group (SC). The experiment lasted for 42 days, with assessments of their intestinal barrier function, inflammatory factors, antioxidant markers, and fecal microbiome composition. The results showed that dietary S. cerevisiae reduced the levels of TNF-α, IL-6, and IL-1β in the serum ( p < 0.05). In the SC group, plasma superoxide dismutase and glutathione peroxidase activities increased, while the level of malondialdehyde significantly decreased ( p < 0.05). Additionally, dietary S. cerevisiae lowered the serum zonulin and lipopolysaccharide (LPS) levels ( p < 0.05) and inhibited fecal ammonia production ( p < 0.05). Furthermore, the microbiota profile showed that dietary S. cerevisiae decreased the abundance of Firmicutes but increased the Chao index, the abundance of Bacteroidetes, and the proportion of Bacteroidetes to Firmicutes ( p < 0.05). To conclude, dietary S. cerevisiae can regulate the gut's microbial structure and gut health, which may contribute to the overall health of companion animals as they age.