Niacin alters ruminal microbial composition and metabolites in sheep fed a high-concentrate diet

This study aimed to investigate the effects of niacin supplementation in a high-concentrate diet on growth performance, rumen fermentation, rumen microbiota, and metabolomics in sheep. Twelve sheep were randomly divided into two groups: (1) a control group (CON, n=6) fed a basal diet; (2) a niacin group (NA, n=6), sheep fed a basal diet supplemented with 130 mg/d niacin. The experiment lasted 26 days, a 14 days for the adaptive phase was followed by 12 days of sampling period. Growth performance (initial body weight, final body weight, and average daily gain) was measured on days 1 to 5 of the sampling period, and rumen fluid samples were collected on days 6 to 7 for the determination of rumen fermentation parameters, lactate metabolism-related enzymes, microbial diversity, and metabolomics.The results showed that 1) The dry matter feed intake of the niacin group was higher than that of the control group (p In summary, adding niacin to high-concentrate diets can significantly improve the growth performance of sheep, improve rumen fermentation and rumen microbial community structure, affect rumen metabolites, and thus alleviate the symptoms of rumen acidosis.