Submitted to: Western Section of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 21, 2001
Publication Date: N/A
Technical Abstract: Ruminal methane (CH4) production is an inefficient process that results in losses of 2-12% of gross energy intake. Presently, we tested the effect of three potential inhibitors of ruminal CH4 production in vitro. Ruminal fluid was incubated (39 deg C) for 24 h under 100% CO2 in closed tubes (10 ml/tube) supplemented with 72 mM formate and 12 mM 2-nitropropanol (2NPOH), ,nitroethane (NE) or nitroethanol (NeOH). Control cultures contained no added nitrocompound. Presented values are the mean +/- SE from n = 3 and tests for significance were accomplished using an analysis of variance. Methane production was reduced (P<0.05) from control incubations (27.6 +/- 2.1 umol/ml rumen fluid) by more than 10-fold by all nitrocompounds (2.6 +/- 0.4, 1.5 +/- 0.4 and 1.4 +/- 0.1 umol/ml for 2NPOH, NeOH and NE, respectively). Concentrations of acetate, propionate and butyrate produced by nitrocompound supplemented cultures were not different (P>0.05) from those produced by control cultures (62.1 +/- 5.1, 15.8 +/- 1.1 and 11.0 +/ 1.91 umol/ml, respectively) indicating that reductant was not redirected toward the production of more reduced fermentation acids. However, H2 did accumulate in incubations supplemented with the nitrocompounds (2.8 +/- 0.2, 2.1 +/- 0.6 and 1.9 +/- 0.2 umol/ml for 2NPOH, NeOH and NE, respectively). Thus, energetic efficiencies associated with microbial interspecies H2 transfer were diminished which suggests that addition of other H2 oxidizing bacteria to the nitrocompound supplemented cultures may preserve an electron sink typically beneficial to the fermentation. Future research in this area may lead to the development of strategies that reduce ruminal CH4 production.