玉树州藏嵩草草地牧草营养价值评定与营养载畜量

为了更为精确地确定三江源区玉树州主要草地类型之一——藏嵩草(Kobresia tibetica)草地的载畜量,本研究选用3头装有永久性瘤胃瘘管的5岁大通牦牛作为试验动物,采用体外产气法和概略养分分析法,评定了玉树州藏嵩草草地类型天然牧草营养价值,结合该地区的产草量,核定数量载畜量和营养载畜量。研究表明,1)藏嵩草草地天然牧草鲜草产量为1 272 g·m-2,风干草样为349.04 g·m-2,可食牧草产量为341.29 g·m-2;2)藏嵩草草地牧草中粗蛋白(CP)、粗脂肪(EE)、酸性洗涤纤维(ADF)、粗灰分(Ash)、钙(Ca)、磷(P)含量分别为10.16%、2.26%、34.07%、4.76%、0.31%、0.11%;3)藏嵩草草地牧草体外产气评定得出,120 h估测有机物质消化率(DOM)、体外干物质消化率(IVDMD)、消化能(DE)、代谢能(ME)分别为81.21%、62.67%、10.33 MJ·kg-1、9.16 MJ·kg-1,体外发酵后瘤胃液氨氮(NH3-N)浓度为7.72 mg·dL-1,pH为6.65,体外培养过程中,产气速率变化曲线呈现单峰形(20―28 h)。4)数量载畜量约为1 411万个羊单位(合8.44个羊单位·hm-2),营养载畜量中可消化粗蛋白(DCP)和ME载畜量分别为2 202万个羊单位(合13.16个羊单位·hm-2)和2 051万个羊单位(合12.26个羊单位·hm-2)。

Study on evaluation of forage nutritions and nutritional carrying capacity in grassland of Kobresia tibetica grassland in Yushu Prefecture

In order to evaluate the carrying capacity of Kobresia tibetica grassland which was one of the main grassland types in Yushu Prefecture, three Datong yaks (five years old) were chosen to provide rumen solution, nutritional value of forage in K. tibetica grassland from Yushu prefecture belonged to Sanjiangyuan Region, and were evaluated in vitro with gas production method and conventional nutritional analysis method, and combined with forage yield, the carrying capacity of K. tibetica grassland was calculated. The results were as follows: 1) the yield of fresh forage, dry forage and edible forage of K. tibetica forageland were 1 272, 349.04, 341.29 g·m-2 respectively; 2) CP, EE, ADF, Ash, Ca, P were 10.16%, 2.26%, 34.07%, 4.76%, 0.31%, 0.11%, respectively; 3) the values of DOM, DE and ME were estimated according to the content of CP, EE and gas production of 120 h, which were 81.21%, 10.33 MJ·kg-1, 9.16 MJ·kg-1, respectively, and dry matter digestibility (DMD), ammonia nitrogen concentration(NH3-N), pH value were 62.67%, 7.72 mg·dL-1 and 6.65, respectively, and the curves of gas production rate showed the shape of single-peak (20―28 h); 4) the carrying capacity of production, ME and DCP for K. tibetica grassland in Yushu Tibetan Autonomous prefecture were 14.11(8.44 sheep units per hectare), 20.51(13.16 sheep units per hectare) and 22.02(12.26 sheep units per hectare) million sheep units approximately.