梯度添加硝酸盐或硫酸盐对瘤胃体外发酵和总菌数量的影响

摘要

为研究梯度添加硝酸盐或硫酸盐是否对瘤胃微生物有适应性,本试验以3只安装永久性瘤胃瘘管的成年萨能奶山羊为瘤胃液供体,应用体外产气法研究梯度添加硝酸盐或硫酸盐对瘤胃液批次发酵参数和总菌数量的影响.试验设对照组、硝酸盐组和硫酸盐组.处理组在第1~5 d梯度添加2~5 mmol/L硝酸钠或硫酸钾,初始终浓度均为2 mmol/L,以1 mmol/(L·d-1)增加至5 mmol/L后保持浓度不变继续发酵24 h,分别检测1~5 d总产气量、pH、挥发性脂肪酸(VFA)、NH3-N和总菌数量.结果显示:1)第3~5天添加2~5 mmol/L硝酸盐可显著降低总产气量(P<0.05),第1天添加2 mmol/L硫酸盐显著降低总产气量(P<0.05);2)添加2~5 mmol/L硝酸盐或硫酸盐对TVFA均无影响(P>0.05),但会不同程度地影响各VFA的浓度和百分比;3)添加2 mmol/L硝酸盐对第1 d NH3-N有提高趋势(P<0.10),显著提高了第2~5天NH3-N含量(P<0.05);第1~4天添加2~5 mmol/L硫酸盐显著提高第5天 NH3-N含量(P<0.05);4)添加2~5 mmol/L硝酸盐和硫酸盐均对总菌数量无显著影响(P>0.05).结果表明:梯度添加硝酸盐或硫酸盐可提高瘤胃批次发酵NH3-N含量,均不影响发酵液TVFA和总菌数量.%The present study focused on effects of gradient addition of nitrate or sulfate on rumen fermentation and the total bacteria count by batch fermentation with the method of in vivo gas production, aiming to investigate gradient addition of nitrate or sulfate on the adaptation of rumen microbes.The fluid was collected from three fistulated Xinong Saanan dairy goats.Experiment design contained addition of sodium nitrate, potassium slufate and the control with neither of them.The treatment was added 2-5 mM nitrate or sulfate in 5 days by grads.Total gas, pH, volatile fatty acids (VFA), ammonia and the number of total bacteria count were measured.Results showed: (1) The volumes of the total gas were significantly lower with addition of 2~5 mM nitrate in 3 to 5 days (P<0.05) and addition of slufate on the first day, whereas, on other days, inclusion of nitrate or sulfate had no difference on the volumes of the total gas (P>0.05).(2) In a way, addition of 2~5 mM nitrate or sulfate changed the concentration and proportion of VFAs, but had no difference on TVFA (P>0.05);with the increasing of nitrate, the ratio of acetate to propionate decreased gradually.(3) Addition of 2 mM nitrate had a trend of ammonia increasing (P<0.1) and 3~5 mM increased ammonia significantly in 2 to 5 days (P<0.05);In the first four days, inclusion of 2~5 mM slufate did not change ammonia compared with the control, but increased ammonia significantly on the last day (P<0.05);(4) Addition of 2~5 mM nitrate or sulfate had no significant effect on the number of total bacteria (P>0.05).Therefore, it is concluded that gradient addition of nitrate or sulfate had no significant inhibitory effect on the fermentation parameters and total bacteria count in batch cultures.