体外产气法评价青海高原反刍家畜常用粗饲料组合效应

采用体外产气法评价青海高原反刍家畜的3种常用粗饲料青贮玉米（Zea mays）秸秆、苜蓿（Medicago sativa）青干草和燕麦（Arrhenatherum elatius）青干草按0∶100、25∶75、50∶50、75∶25和100∶0的比例两两组合时的发酵特性。结果表明，理论最大产气量、48 h产气量分别与中性洗涤可溶物/粗蛋白（NDS/CP）（P＜0.001）、有机物（OM）（P＜0.01），中性洗涤可溶物（NDS）（P＜0.05）呈正相关关系，分别与酸性洗涤纤维（ADF）（P＜0.001）、中性洗涤纤维（NDF）（P＜0.05）和粗蛋白（CP）（P＜0.05）呈负相关关系；产气速率常数分别与OM（P＜0.001）、NDS（P＜0.001）和NDS/CP（P＜0.01）呈正相关关系，分别与ADF、NDF均呈极显著负相关关系（P＜0.001）；产气延滞时间与ADF（P＜0.01）和NDF（P＜0.05）呈正相关关系，分别与OM（P＜0.01）、NDS（P＜0.05）和NDS/CP（P＜0.05）呈负相关关系，说明了组合牧草体外发酵产气程度主要受非结构性碳水化合物与粗蛋白比例的影响。3种粗饲料两两组合搭配时，青贮玉米秸秆与苜蓿青干草以25∶75比例、青贮玉米秸秆与燕麦青干草以50∶50比例、苜蓿青干草与燕麦青干草以25∶75或50∶50比例组合时较为合适，且随着发酵时间的延长，各组合均呈现组合效应量逐渐减弱的变化趋势。

Evaluation of associate effects of ruminants forages in the Qinghai Plateau using in vitro gas production technique

The in vitro gas production technique was used to evaluate associate effects of mixed with two ruminants forages of silage corn straw, alfalfa green hay and oat green hay with 0∶100, 25∶75, 50∶50, 75∶25 and 100∶0 in the Qinghai plateau. This study showed that 48 h gas production and theoretical maximum gas production were positively related to the content of NDS/CP(P＜0.001), OM(P＜0.01), NDS(P＜0.05), and negatively related to the content of ADF(P＜0.001), NDF(P＜0.05), CP(P＜0.05). Gas producing velocity were positively related to the content of OM(P＜0.001), NDS(P＜0.001), NDS/CP(P＜0.01), and negatively related to the content of ADF(P＜0.001), NDF(P＜0.001). The lag times of gas production were positively related to the content of ADF(P＜0.01), NDF(P＜0.05), and negatively related to the content of OM(P＜0.01), NDS(P＜0.05), NDS/CP(P＜0.05), and these results showed the fermentation level of combined forages in vitro gas production were mainly affected by the proportion of non structural carbohydrates and crude protein. When the forages are mixed, combination proportion of silage corn straw and alfalfa hay by 25∶75, silage corn straw and oats by 50∶50, alfalfa green hay and oat green hay by 50∶50 were relatively appropriate, and with the increase of fermentation time, associate effects quantity of each combinations showed a gradually decreasing trends.