中文摘要：

本文研究了大蒜素对藏羊瘤胃液体外培养青藏高原高寒草甸4期牧草体外发酵及甲烷产量的影响。选取2只健康、年龄相近的瘘管藏羊为瘤胃液供体,采用体外产气法,全年4期牧草作为发酵底物,分别添加0、0.5%、1.0%、1.5%和2.0%的大蒜素,筛选出最佳添加量。结果表明,各期累积产气量随大蒜素添加量的增多均呈下降趋势,1.5%和2.0%组均显著下降,甲烷产量均显著降低;对各期p H影响不显著;大蒜素1.0%以上时,枯草期NH3-N浓度下降显著,返青期2.0%时下降显著,青草期无显著变化,返青期和枯黄期0.5%和1.0%时升高显著;大蒜素0.5%以上时,枯草期短链脂肪酸（short chain fatty acid,SCFA）下降显著,返青期2.0%时下降显著,青草期无显著变化,枯黄期1.0%以上时下降显著;大蒜素2.0%时,枯草期、返青期和枯黄期有机物质消化率（organic matter digestibility,OMD）下降显著,青草期无显著变化;大蒜素0.5%以上时,枯草期代谢能（metabolic energy,ME）下降显著,返青期、青草期和枯黄期均无显著变化;各期泌乳净能（net energy of lactation,NEL）仅枯草期大蒜素为2.0%时下降显著,其余组无显著变化。大蒜素作为藏羊日粮添加剂的适宜添加量为0.5%-1.0%。

英文摘要：

Effects of allicin on fermentation and methane emissions of in vitro Tibetan sheep with Qinghai-Ti-bet Plateau alpine meadow for four periods pastures were studied in the paper. Two healthy and age closed Tibetansheep with fistulad were used as rumen fluid donor, and in vitro technique adopted. Pastures of four periods in a year were used as substrate, and 0%, 0.5%, 1.0%, 1.5% and 2.0% of allicin were added to screen the optimum addi-tive amount. Results showed that cumulative gas production in each period decreased with the increment of allicin.When 1.5% and 2.0% of allicin were added, the decline were significant, and methane emissions decreased signifi-cantly. p H value in each group was almost consistent. When more than 1.0% allicin added in withered period and2.0% in back green period, the NH3-N concentration significantly declined. It had no effect on green period, butNH3-N concentration rose significantly if 0.5% of allicin added to back green period or 1.0% of allicin added to yellow period. when above 0.5% of allicin added in withered period, or 2.0% in back green period, or 1.0% in yellowperiod, short chain fatty acid（SCFA） declined significantly. It did not changed when added in green period. Exceptof green period, organic matter digestibility（OMD） declined significantly as allicin amount reach to 2.0%. Whenabove 0.5% of allicin added in withered period, the metabolic energy（ME） decreased significantly, whereas in otherthree periods it was steady. When 2.0% of allicin added in withered period, the net energy of lactation（NEL） decreased significantly, whereas in other three periods it was steady. Therefore, when allicin was used as feed additives of Tibetan sheep, it＇s optimum amount was 0.5%-1.0%.