添加糖蜜与乳酸菌对燕麦秸杆和黑麦草混合青贮品质的影响

为探讨西藏地区燕麦（Avena sativa L.）秸秆和多年生黑麦草（Lolium perenne L.）混合青贮使用添加剂改善发酵品质的措施，进一步提高燕麦秸秆利用效率，将收获籽粒后的燕麦秸秆和抽穗期刈割的多年生黑麦草以4∶6混合青贮，分别添加1×10⁶ cfu·g^-1 FW的乳酸菌制剂、4% FW糖蜜和乳酸菌+糖蜜，青贮60 d后取样分析青贮饲料发酵品质。结果表明：单独或组合添加糖蜜和乳酸菌均不同程度的改善了混合青贮发酵品质，显著降低了pH值、氨态氮/总氮、丙酸和丁酸含量（P<0.05），显著提高了乳酸含量和乳酸/乙酸（P<0.05）。添加糖蜜组发酵品质优于添加乳酸菌组，显示较高的乳酸和水溶性碳水化合物含量（P<0.05），且单独添加糖蜜与组合添加组各发酵指标无显著差异。综合考虑，在燕麦秸秆和多年生黑麦草（4∶6）混合青贮时添加4%糖蜜较为适宜。

Effects of Adding Molasses and Lactic Acid Bacteria on the Fermentation Quality of Mixed Silage of Oat Straw and Perennial Ryegrass

To improve the fermentation quality of mixed silage of oat straw and perennial ryegrass and enhance the utilization efficiency of oat straw resource in Tibet, the mixture of oat straw and perennial ryegrass (4:6) were ensiled with different additives. The treatments were designed as follows: control, lactic acid bacteria (LAB, 1×10⁶ cfu·g^-1 FW), molasses (4% FW) and LAB + molasses, six reduplicate silos per treatment. The fermentation quality was analyzed after ensiling 60 days. Molasses or/and LAB additives significantly decreased the pH value, ammonia/total N (AN/TN), propionic and butyric acid contents of mixed silage (P<0.05), while significantly increased the lactic/acetic acid ratio and lactic acid contents of mixed silage compared to control silage (P<0.05). The silage added with molasses had higher lactic acid and water soluble carbohydrate (WSC) contents than the one added with LAB. However, there was no significantly different fermentation quality between the silage added with molasses and the one added with LAB + molasses. Therefore, it was suggested that 4% molasses additive was suitable to improve the fermentation quality of mixed silage of oat straw and perennial ryegrass in Tibet.