添加剂对西藏混合青贮发酵品质和有氧稳定性的影响

为评价添加糖蜜、山梨酸钾和山梨酸钾+糖蜜对西藏地区燕麦(Avena sativa)和紫花苜蓿(Medicago sativa)(7:3)混合青贮发酵品质和有氧稳定性的影响,设对照组(C),4%糖蜜组(M),0.15%山梨酸钾组(S)和山梨酸钾+糖蜜(S+M)4个处理,青贮后第30,45,60 d开窖取样,测定青贮饲料的发酵品质,其他青贮窖在发酵60 d后全部打开,暴露于空气中5,10,15 d后取样分析其有氧稳定性.结果表明:与对照组相比,M组及S+M组pH显著降低,乳酸含量显著升高(P<0.05),有效地改善了混合青贮发酵品质,S组改善效果不显著.有氧暴露过程中,对照组和M组pH值迅速升高,乳酸含量显著减少(P<0.05),S组和S+M组的pH值、乳酸、水溶性碳水化合物等含量相对稳定.表明S+M组既能提高燕麦和紫花苜蓿混合青贮发酵品质,又能改善有氧稳定性.

Effects of Additives on the Fermentation Quality and Aerobic Stability of Mixed Silages in Tibet

In order to evaluate the effects of adding molasses, potassium sorbate and their combinations on the fermentation qualities and aerobic stability of mixed silages of 70% oat (Avena sativa)and 30% alfalfa(Medicago sativa), 4 treatments were prepared as follows: control (C), 4% molasses (M), 0.15% potassium sorbate (S), potassium sorbate+ molasses (S+M). Silos were opened on the 30, 45, 60^th day of ensiling, respectively, and the fermentation quality was analyzed. The rest silos were opened to expose to the air after ensiling 60 days. Chemical analyses were carried out on the 5, 10, 15^th days after exposing to air. M and S+M treatments had significantly lower pH values and higher lactic acid contents(P<0.05)compared to control, indicating that the addition of M and S+M improved the fermentation quality of mixed silages efficiently. However, S was unavailable to improve fermentation quality. During aerobic exposure, the pH values of the control and M treatment increased rapidly, the contents of lactic acid reduced significantly(P<0.05). The pH values and the contents of lactic acid and water soluble carbohydrate of the S and the S+M treatments were relatively stable. Based on results, the S+M was practicable to improve fermentation quality with better aerobic stability.