Fermented Feed Supplement Relieves Caecal Microbiota Dysbiosis and Kidney Injury Caused by High-Protein Diet in the Development of Gosling Gout

SIMPLE SUMMARY: Recently, high-protein complete feed has been increasingly used in the Chinese goose industry, increasing the outbreaks of gout in goslings. We found that high-protein diets are implicated in the kidney injury and gut microbiota dysbiosis associated with the occurrence of gout in goslings. Fermented feed, containing many helpful intestinal probiotics and metabolites for birds, shows potential for the protection of gut microbiota. We found that fermented feed supplement alleviates the gout occurrence caused by the high-protein diets and improves renal function, because of its regulations of caecal microbiota. Fermented feed increased Lactobacillus and decreased Enterococcus in the cecum of goslings. We suggest that goose farmers should strictly control the proportion of protein in gosling feed and consider using fermented feed as an effective measure to control the outbreak of gosling gout. ABSTRACT: Firstly, forty-eight 1-day-old goslings were randomly allocated to four groups and were fed diets containing crude protein (CP) at different concentrations: 160, 180, 200, and 220 g/kg in Experiment One. We found a dose-dependent relationship between the dietary protein levels and morbidity of gosling gout. The concentration of serum uric acid (UA), creatinine (Cr), and urea nitrogen (UN), and the activity of xanthine oxidase in the 220CP groups were significantly higher than those in the low-protein diet groups. Beneficial microbes, including Akkermansia, Lactococcus, and Butyricicoccus were enriched in the ceca of healthy goslings, while the microbes Enterococcus, Enterobacteriaceae, and Bacteroides were enriched in those with gout. Then, we explored the effects of fermented feed on gosling gout caused by high-protein diets in Experiment Two. A total of 720 1-day-old goslings were randomly allotted to four experimental groups: CN (162.9 g/kg CP), CNF (167.5 g/kg CP, replacing 50 g/kg of the basal diet with fermented feed), HP (229.7 g/kg CP, a high-protein diet), and HPF (230.7 g/kg CP, replacing 50 g/kg of the high-protein diet with fermented feed). We found that the cumulative incidence of gout increased in the HP group compared with that in the control, but decreased in the HPF group compared to that in the HP group. Similarly, the concentration of serum UA in the HP group was higher than that in the CN group, but decreased in the HPF group. Meanwhile, compared with the HP group, using fermented feed in diets decreased the abundance of Enterococcus in the ceca of goslings, while increasing the abundance of Lactobacillus. These results suggest that appropriate dietary protein levels and the fermented feed supplement might relieve the kidney injury and gut microbiota dysbiosis caused by high-protein diets in the development of gosling gout.