本文旨在通过化学分析和活体外人工瘤胃产气法测定西藏高寒草地冷暖季牧草的化学成分和产气量,研究西藏高寒草地牧草对牦牛的营养价值及养分可提供量。采用单因子试验设计,试验处理为4种采自当雄和那曲的暖季牧草和冷季牧草,分别记为当雄暖季牧草、当雄冷季牧草、那曲暖季牧草和那曲冷季牧草。人工瘤胃产气法的瘤胃液供体动物为3头安装永久性瘤胃瘘管的大通牦牛。结果表明:4种牧草间粗脂肪(EE)、酸性洗涤木质素和酸洗剂不溶蛋白(ADICP)含量均无显著差异(P>0.05),但干物质(DM)、粗蛋白质(CP)、粗纤维(CF)、粗灰分(Ash)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和中洗剂不溶蛋白(NDICP)含量均有显著差异(P<0.05)。无论是来源于当雄还是那曲,暖季牧草的DM、CP、Ash和NDICP含量均显著高于冷季牧草(P<0.05),而CF、NDF和ADF含量显著低于冷季牧草(P<0.05),表明暖季牧草的营养价值高于冷季牧草。西藏高寒草地每公顷暖季牧草的干草、OM、CP、总消化养分(TDN)和代谢能(ME)产量分别为629.7 kg、519.9 kg、111.9 kg、354.1 kg和5 666.4 MJ;每公顷冷季牧草的干草、OM、CP、TDN和ME产量分别为3 001.6 kg、2 547.9 kg、432.9 kg、1 709.3 kg和25 542.0 MJ。根据西藏全区高寒草地面积和每公顷牧草营养物质产量,估测出全区干草、OM、CP、TDN和ME年产总量分别为1 899.9万t、1 591.5万t、304.7万t、1 075.4万t和1 661.5亿MJ。全区高寒草地每年提供给家畜采食的牧草量可以满足2 814.7万个绵羊单位的全年消耗。

The chemical composition and in vitro gas production were measured using chemical analyses and in vitro gas production method of artificial rumen to investigate the nutritive values and nutrient supply of cold- and warm-season pastures from high-cold steppes of Tibet region. Four pastures from cold- and warm-seasons in Dangxiong and Naqu (WSP-DX, CSP-DX, WSP-NQ and CSP-NQ) were used as treatment feedstuffs in a single factor experimental design. Rumen fluid used in the in vitro gas production test was taken from 3 Datong donor yaks with permanent rumen fistulas. The results showed that the contents of ether extract (EE), acid detergent lignin (ADL) and acid detergent insoluble protein (ADICP) had no significant differences among 4 pastures (P>0.05), while there were significant differences in the contents of dry matter (DM), crude protein (CP), crude fiber (CF), crude ash (Ash), neutral detergent fiber (NDF), acid detergent fiber (ADF) and neutral detergent insoluble protein (NDICP), respectively (P>0.05). No matter where from Dangxiong or Naqu, compared with cold-season pasture, warm-season pasture had higher contents of DM, CP, Ash and NDICP (P<0.05), but had lower contents of CF, NDF and ADF, indicating that the nutritive value of warm-season pasture was higher than that of cold-season pasture. The productions of hay, organic matter (OM), CP, total digestible nutrient (TDN) and metabolizable energy (ME) of warm-season pasture were 629.7 kg, 519.9 kg, 111.9 kg, 354.1 kg and 5 666.4 MJ per hectare, respectively, and the corresponding parameters of cold-season pasture were 3 001.6 kg, 2 547.9 kg, 432.9 kg, 1 709.3 kg and 25 542.0 MJ per hectare, respectively. The annual productions of hay, OM, CP, TDN and ME in whole Tibetan rangelands were estimated to be 18.999 million tons, 15.915 million tons, 3.047 million tons, 10.754 million tons and 166.15 billion MJ based on nutrient productions per hectare and whole rangeland size of Tibet, respectively. Total available pasture production can meet the annual consumption for 28.147 million sheep units.