Decreasing ruminal methane production through enhancing the sulfate reduction pathway

Abstract

Methane (CH4) production from ruminants accounts for 16% of the global greenhouse gas emissions and represents 2% to 12% of feed energy. Mitigating CH4 production from ruminants is of great importance for sustainable development of the ruminant industry. H2 is the primary substrate for CH4 production in the processes of ruminal methanogenesis. Sulfate reducing bacteria are able to compete with methanogens for H2 in the rumen, and consequently inhibit the methanogenesis. Enhancing the ruminal sulfate reducing pathway is an important approach to mitigate CH4 emissions in ruminants. The review summarized the effects of sulfate and elemental S on ruminal methanogenesis, and clarified the related mechanisms through the impacts of sulfate and elemental S on major ruminal sulfate reducing bacteria. Enhancing the activities of the major ruminal sulfate reducing bacteria including Desulfovibrio, Desulfohalobium and Sulfolobus through dietary sulfate addition, elemental S and dried distillers grains with solubles can effectively decrease the ruminal CH4 emissions. Suitable levels of dietary addition with different S sources for reducing the ruminal CH4 production, as well as maintaining the performance and health of ruminants, need to be investigated in the future.