Authors : Caixia Shi, Qingxiang Meng, Xianzhi Hou, Liping Ren and Zhenming Zhou
Abstract: Researchers evaluated the response of ruminal fermentation, methane production and dry matter digestibility to microbial source and nitrate addition level in an in vitro incubation using rumen microbes from wethers fed a diet with or without supplementary nitrate. Potassium nitrate was added to the fermentation substrates in vitro to form three different levels of nitrate-N (4, 8 and 16 g kg-1 DM). Compared with microbial source from urea diet-fed wethers, ruminal microbes from nitrate diet-fed animals had increased total gas production, CH4 and CO2 production, acetate molar proportion and DM digestibility but had decreased ruminal nitrite accumulation, NH3-N concentration, total VFA production and molar proportion of propionate and butyrate. There was no effect of interaction between microbial source and nitrate-N addition level on ruminal fermentation characteristics, methane production and dry matter digestibility. Along with the increase of nitrate- N addition level, production of CH4 and CO2 and molar proportion of propionate were reduced whereas residual concentrations of both nitrate and nitrite in the incubation medium were increased. Nevertheless, total VFA production and DM digestibility was not affected by nitrate-N addition level in vitro. In conclusion although, nitrate addition has ability to inhibit ruminal methane production, the inhibition ability would gradually vanish after the microbes acclimate to the nitrate diet. The results imply that nitrate has a potential value as a dietary nitrogen supplement used by ruminant animals.
Caixia Shi, Qingxiang Meng, Xianzhi Hou, Liping Ren and Zhenming Zhou, 2012. Response of Ruminal Fermentation, Methane Production and Dry Matter Digestibility to Microbial Source and Nitrate Addition Level in an in vitro Incubation with Rumen Microbes Obtained from Wethers. Journal of Animal and Veterinary Advances, 11: 3334-3341.