青藏高原不同海拔区垂穗披碱草的发酵性能

Fermentation properties of ensiled Elymus nutans from different altitude regions on the Tibetan Plateau

为明确青藏高原海拔对垂穗披碱草(Elymus nytans)青贮饲料发酵品质的影响,本研究以不同海拔区(天祝2 965m、果洛3 763m、当雄4 228m和那曲4 752m)的垂穗披碱草为发酵原料,测定其在青贮14、30、60、90d后的青贮指标。结果表明,随海拔的升高,垂穗披碱草附着乳酸菌数量呈升高趋势,酵母数量呈下降趋势,而霉菌数量受海拔影响小;时间和海拔的互作极显著影响pH、乳酸、乙酸含量和霉菌的数量(P<0.001);不同海拔地区的垂穗披碱草同一青贮时间的pH、干物质、乳酸和乙酸的含量以及微生物数量均存在差异(P<0.05),且那曲和果洛地区垂穗披碱草青贮饲料的发酵品质优于天祝和当雄地区;当青贮90d时,随海拔的升高,可溶性糖呈降低趋势,粗蛋白呈上升趋势。上述结果表明,在高海拔的那曲和果洛地区,青贮有利于垂穗披碱草保存更多的营养价值。

Abstract： In order to evaluate the effect of altitude on the quality of Elyrnus nutans silage, we studied the fer- mentation quality （silage quality and nutritional content） of E. nutans from different altitudes （Tianzhu, 2 965 m, Golok, 3 763 m, Damxung, 4 228 m and Nagchu, 4 752 m） on the Qinghai-Tibet plateau after fermentation for 14, 30, 60, and 90 days. The results showed that the number of epiphytic lactic acid bacteria in E. nutans increased and the yeast count decreased, whereas the amount of fungus in the E. nutans was unaffected by the increase in altitude. The differences in the time and regions significantly affected the pH, the lactic acid and acetic acid content, and the number of fungi （P〈0.001）. Additionally, the comparison of ensiled the E. nutans from different altitude regions revealed significant differences in the pH, the content of lactic acid and acetic acid, and microbial composition （P〈0.05） ; the fermentation properties of E. nutans in the Golok and Nagchu regions were superior to the other two regions. Finally, the characteristics of F.. nutans in the 90 day fermentation period indicated that the content of water-soluble carbohydrate decreased with an increase in altitude,whereas the content of crude protein increased. In conclusion, the use of ensiled E. nutans from Golok and Nagchu will provide greater nutritional value.