Control of methanogenesis and impovement of fiber digestion in the rumen

为降低瘤胃产甲烷率进行了研究，获得了以下结果：(1)添加富马酸可在不抑制纤维体外消化的情况下减少产甲烷率。筛选富马酸降解菌，明确影响富马酸还原酶活性的因素。(2)克隆了编码磷酸烯醇式丙酮酸羧酸激酶和丙酮酸激酶的基因，并对转录调控因子进行了检测。结果表明，增加富马酸还原途径可以减少富马酸还原途径。(3)硝酸盐还原和亚硝酸盐还原降低了甲烷生成。硝酸还原酶是由硝酸盐诱导的。添加电子供体如乳酸和甲酸盐可促进硝酸盐和亚硝酸盐的还原。这表明控制发酵以增加乳酸和甲酸盐会增加硝酸盐和亚硝酸盐的还原，从而减少甲烷的产生。(4)中链脂肪酸、桉树油和环糊精结合的卤素(CCH)在体外减少了甲烷的产生并刺激了丙酸的产生。(5)给牛添加富马酸或四氯环己烷可减少产甲烷，提高丙酸产量，提高干物质和NDF的消化率。(6)建立了瘤胃普氏杆菌和牛链球菌的宿主载体系统，可用于该细菌的基因操作。

Attempts were made to reduce methanogenesis in the rumen, and the following results were obtained.(1) Addition of fumarate reduced methanogenesis without depressing fiber digestion in vitro.Fumarate-reducing bacteria were selected, and factors affecting fumarate reductase activity were clarified.(2) Genes encoding phosphoenolpyruvate carboxykinase and pyruvate kinase were cloned, and factors regulating the transcription were examined. The results suggested that the fumarate-reducing pathway could be reduced by increasing. methanogenesis(3) Methanogenesis was decreased by nitrate and nitrite reduction. Nitrate reductase was shown to be induced by nitrate. Addition of electron donors such as lactate and formate stimulated nitrate and nitrite reduction. This suggests that control of fermentation to increase lactate andformate increases nitrate and nitrite reduction, which reduces methanogenesis.(4) Middle-chain fatty acids, eucalyptus oil, and cyclodextrin-conjugated halogens (CCH) reduced methanogenesis and stimulated propionate production in vitro. (5) Administration of fumarate or CCH to cattle reduced methanogenesis, enhanced propionate production, and enhanced the digestibility of dry matter and NDF.(6) Host-vector systems for Prevotella ruminicola and Streptococcus bovis were established, which can be used for gene manipulation of the bacteria.