In vitro and in vivo analysis of rumen fermentation after supplementary niacin in high concentrated fed cattle.

Rumen acidosis is a common nutritional metabolic disease in ruminants, and the developing of feed additives to prevent this disorder has great application prospect. This study was conducted to investigate the effects of dietary niacin supplementation with different concentrate to roughage ratio on rumen fermentation evaluated by simulated rumen fermentation in vitro and in vivo. The cattle fed with basal feed (dietary concentrate-to-forage ratio was 5: 5) and high concentrate feed (dietary concentrate-to-forage ratio was 8: 2) were defined as Control stage and HC stage, respectively. The HCN was defined as the cattle were fed with high concentrate feed with supplementary niacin (800 mg/kg). Three healthy male Jinjiang cattle were used as rumen fluid donors in the in vitro experiment and in vivo experiment, finally the fermentation parameters were determined. The results showed: dietary niacin retards the decline of pH induced by high concentrate diet via regulation of lactic acid produce in both in vitro and in vivo fermentation; dietary niacin inhibited the increased production of VFAs induced by high concentrate diet in in vitro fermentation; dietary niacin also affected the production of microbial proteins (MCP), gas and NH3-N. The present study provided baseline data to indicate that the niacin had the potential to use as a feed additive to prevent the occurrence of rumen acidosis in cattle.