College of Animal Science and Technology and State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, China.
Department of Animal Sciences, The Ohio State University, Columbus, OH, USA.
J Appl Microbiol. 2019 Jul;127(1):150-158. doi: 10.1111/jam.14286. Epub 2019 May 21.
This study investigated the effects of ferric citrate, nitrate and saponin, both individually and in combination, on sulphidogenesis, methanogenesis, rumen fermentation and abundances of select microbial populations using in vitro rumen cultures.
Ferric citrate (50 mg l ), Quillaja saponin (0·6 g l ) and sodium nitrate (5 mmol l ) were used in in vitro ruminal fermentation. Ferric citrate alone, its combination with saponin and/or nitrate lowered the aqueous sulphide concentration and total sulphide production. Methane production was suppressed by nitrate alone (by up to 32·92%), its combination with saponin (25·04%) and with both saponins with nitrate (25·92%). None of the treatments adversely affected feed digestion or rumen fermentation. The population of sulphate-reducing bacteria was increased by nitrate and saponin individually, while that of total Archaea was decreased by nitrate alone and the combination of the three inhibitors.
Nitrate and its combination with saponin or both ferric citrate and saponin substantially decreased methane production. Most importantly, the decreased methane production was not at the expense of feed digestion or fermentation. Sulphidogenesis from the sulphate present in the high-sulphur diets can be suppressed competitively by ferric citrate, although it was elevated by saponin and nitrate.
The results of this study demonstrated that combinations of certain methane inhibitors, which have different mechanisms of antimethanogenic actions or inhibit different guilds of microbes involved in methane production and sulphate reduction, can be more effective and practical than individual inhibitors, not only in mitigating enteric methane emission but also in lowering the risk of sulphur-associated polioencephalomalacia in feedlot cattle fed high sulphur diets.
本研究采用体外瘤胃培养方法，研究柠檬酸铁、硝酸盐和皂角苷单独及联合使用对硫化物生成、产甲烷、瘤胃发酵和特定微生物种群丰度的影响。
在体外瘤胃发酵中使用柠檬酸铁（50mg/L）、皂角苷（0.6g/L）和硝酸钠（5mmol/L）。柠檬酸铁单独使用，以及与皂角苷和/或硝酸盐联合使用，降低了水相硫化物浓度和总硫化物生成量。硝酸盐单独使用（降低 32.92%）、与皂角苷联合使用（降低 25.04%）以及与皂角苷和硝酸盐联合使用（降低 25.92%）均可抑制甲烷生成。这些处理均未对饲料消化或瘤胃发酵产生不利影响。硝酸盐和皂角苷单独使用均可增加硫酸盐还原菌的数量，而硝酸盐单独使用和三种抑制剂联合使用均降低了总古菌的数量。
硝酸盐及其与皂角苷或柠檬酸铁与皂角苷的组合均显著降低了甲烷生成量。最重要的是，减少甲烷生成量并不以牺牲饲料消化或发酵为代价。高硫日粮中存在的硫酸盐的硫化物生成可以被柠檬酸铁竞争性抑制，尽管皂角苷和硝酸盐会提高硫化物生成。
本研究结果表明，某些甲烷抑制剂的组合，具有不同的抗甲烷作用机制或抑制参与甲烷生成和硫酸盐还原的不同微生物群，可能比单一抑制剂更有效和实用，不仅可以减轻肠道甲烷排放，还可以降低高硫日粮饲养的牛群发生硫相关脑白质软化症的风险。
