不同化学处理对稻草体外发酵动态变化的影响

Effects of different chemical treatments on fermentation characteristics of rice straw in vitro

采用瘤胃体外发酵技术评定了不同化学处理对稻草体外发酵特性的影响。试验以3头装有永久性瘤胃瘘管的荷斯坦奶牛为瘤胃液供体,用复合碱、氨及尿素处理稻草后,称量1g样品于含有10mL瘤胃液和90mL培养基的39℃发酵瓶内体外发酵,分别于24,48,72,96h冰浴终止发酵,测定产气量、发酵液中挥发性脂肪酸、氨态氮及微生物蛋白浓度。结果表明,化学处理提高了稻草发酵的产气量、挥发性脂肪酸、氨态氮以及微生物蛋白浓度。其中复合碱处理组的发酵速度最快,累计产气量、干物质消失率和挥发性脂肪酸浓度最高,显著高于其他各组,其次为尿素处理组和氨化处理组,对照组最低;尿素处理组的pH、氨态氮浓度和微生物蛋白含量最高,显著高于其他各组,氨化处理组和碱化处理组次之,对照组最低。化学处理提高了稻草的体外降解率,其中复合碱化处理的效果最好。

The effects of different chemical treatments on fermentation characteristics of rice straw （RS） in vitro were investigated. The rumen fluid was collected from 3 holstein dairy cows with permanent rumen fistula. The rice straw was treated with composite sodium hydroxide （SH）, ammonium bicarbonate （AB） and urea （UR）. The bottles containing 10 mL rumen fluid and 90 mL media with 1 g RS as substrate were incubated at 39℃, and the samples were collected at 24, 48, 72 and 96 h after incubation for the analysis of gas production （GP）, volatile fatty acids （VFA）, ammonia nitrogen （NH3-N） and microbial protein production （MCP）. The chemical treatments significantly improved the GP, concentrations of VFA, NHs-N and MCP compared with untreated RS. The cumulative gas production, dry matter digestibility and VFA of SH-RS were significantly higher than the others and they were significantly lower in the untreated RS. However, pH and the concentrations of NH3-N and MCP of UR-RS were significantly higher than those of AB-RS, SH-RS and UT-RS. In conclusion, chemical treatments improved the in vitro digestibility of RS, in which composite sodium hydroxide treatment was recommended.