西藏地区不同牧草体外发酵特性研究

摘要

The article aimed to assess the nutritional value of different pastures in Tibet using in vitro gas production technique.Five kinds of common pasture were selected in Tibet,the cumulative gas production after 48 h fermentation (V),the theoretical maximum gas production (Vf),the initial fractional rate of degradation (FRD0),the elapsed time until half of the maximum gas production (t0.5),in vitro dry matter disappearance (IVDMD),in vitro neutral detergent fiber disappearance (IVNDFD),pH,ammoniacal nitrogen (NH3-N) concentration and volatile fatty acid (VFA) production were determined using in vitro gas production technique by the single factor experimental design.The results showed that after 48 h fermentation in vitro,the V,Vf,FRD0,t0.5,IVDMD and methane (CH4),acetic acid,propionic acid,butyric acid and the total VFA production of tall fescue were significantly higher than those of the other four kinds of pastures (P＜0.05),while the in vitro fermentation pH and the ratio of acetic acid to propionic acid were significantly lower than those of the other four kinds of pastures (P＜0.05).The NH3-N concentration of alfalfa was the highest and it was significantly higher than that of the other four kinds of pastures (P＜0.05).The results demonstrate that tall fescue possesses the best in vitro fermentation effect and it is more easily to be utilized by the rumen microorganisms compared to the other pastures.%本文旨在利用体外产气法评定西藏地区不同牧草营养价值.选取西藏地区5种常见牧草,通过单因素试验设计,利用体外产气法评定5种牧草体外发酵48 h累积产气量、理论最大产气量(Vf)、初始产气速率(FRD0)、达到最大产气量一半时所需时间(t0.5)、体外干物质消失率(IVDMD)、体外中性洗涤纤维消失率(IVNDFD)、pH、氨态氮(NH3-N)浓度以及挥发性脂肪酸(VFA)产量.结果表明,体外发酵48 h后,苇状羊茅体外48 h累积产气量、Vf、FRD0、IVDMD及甲烷(CH4)、乙酸、丙酸、丁酸和总VFA产量均显著高于其他4种牧草(P＜0.05),但其体外发酵pH及乙酸/丙酸显著低于其他4种牧草(P＜0.05);紫花苜蓿体外NH3-N浓度最高,显著高于其他4种牧草(P＜0.05).综上分析,苇状羊茅体外发酵效果最佳,与其他试验牧草相比,更容易被瘤胃微生物降解利用.