Effects of Halogenated Compounds on in vitro Fermentation Characteristics in the Rumen and Methane Emissions

This study was conducted to evaluate effects of halogenated compounds on in vitro rumen fermentation characteristics and methane emissions.A fistulated Holstein cow of 650 kg body weight was used as a donor of rumen fluid.Five kinds of halogenated compounds (bromochloromethane (BCM), 2-bromoethane sulfonic acid (BES), 3-bromopropanesulfonic acid (BPS), chloroform (CLF), and pyromellitic diimide (PMDI) known to inhibit methyl-coenzyme M reductase activity were added to an in vitro fermentation incubated with rumen fluid.The microbial population including bacteria, protozoa, and fungi were enumerated, and gas production including methane and fermentation characteristics were observed in vitro.The pH values ranged from 6.25 to 6.72 in all the treatments, and these showed a similar level at 48 hr.The total gas production in the treatments showed a similar pattern with C at 48 hr, whereas methane production in the treatments was lower (p <0.05) than C. Concentrations of total volatile fatty acids (VFAs) and propionic acid were higher (p <0.05) in the treatments than in C at 12 hr.Therefore, halogenated compounds (BCM, BES, BPS, CLF, and PMDI) inhibited in vitro methane emissions by inhibiting methanogens in the rumen.Further studies on safety are needed.