Effect of Varying Starch Levels with or without Niacin in Complete Feeds on Rumen Fermentation Patterns in Vitro

A study was conducted to investigate the effect of supplementation of different starch levels (2, 4, 6, 8%) with or without niacin in the complete diets on the rumen fermentation patterns. The net gas production (NGP) was significantly (P<0.05) more at 8% starch level with and without niacin diets as compared to other starch levels. The IVOMD at 6 and 8% starch levels with and without niacin was comparable to each other but significantly (P<0.05) more than that at 2 and 4% starch with niacin. The PF at 8% starch level with and without niacin was significantly (P<0.05) less than 6% starch without niacin. The microbial mass production (MMP) and efficiency of microbial mass production (EMMP) at 8% starch level with and without niacin was less (P<0.05) as compared to other starch levels. The available metabolizable energy (ME) of both diets at 8% starch levels was comparable to each other but significantly (P<0.05) more than other dietary treatments. The NDF digestibility in non supplemented diets increased at all levels except at 8% starch level irrespective of niacin supplementation. NGP, PF and MMP were significantly (P<0.05) more at 8% starch level than the lower starch levels. EMMP at 6% starch level irrespective of niacin supplementation was significantly (P<0.05) less than that at 2 and 4% but significantly (P<0.05) more than that at 8% starch level. The ME was significantly (P<0.05) higher at 8% than 2, 4 and 6% starch levels. The NDFD increased non-significantly (P<0.05) as the starch level increased up to 6% then it decreased. The niacin supplementation, irrespective of the starch levels, had no significant effect on NGP, IVOMD, PF, NDFD, MMP, EMMP and ME.