Abstract: In order to explore the impact of early screened low-temperature-tolerant lactic acid bacteria on natural pasture silage fermentation,this experiment used natural pasture as raw material and set up 5 treatments without additives,CH (commercial strain),low-temperature-resistant strain Z906,L12,and compound strain ZL. After 60 days of natural fermentation at room temperature,15℃,and 5℃ the nutritional content,fermentation quality and microbial population were determined. The final results showed that temperature had a significant effect on the silage process of natural grass. As the temperature decreases,dry matter,lactic acid,acetic acid content,and the number of coliform bacteria had a downward trend,while water soluble carbohydrate,acid detergent fiber content,and the number of lactic acid bacteria had an upward trend. At 5℃,the Z906 treatment group had the highest dry matter and crude protein contents,the lowest pH value,the highest lactic acid content,no butyric acid production,and the lowest ammonia nitrogen content. The V-Score rating ranked first with a score of 93.07,and the silage quality was the best. In summary,the application of Z906 strain was the best for natural grass silage in cold regions of northern China.

Key words: Natural pasture, Low-temperature tolerant lactic acid bacteria, Silage, Fermentation quality

摘要： 为了探究前期筛选出耐低温乳酸菌对天然牧草青贮发酵的影响，本试验以天然牧草为原料，设置无添加剂、CH(商用菌株)、耐低温菌株Z906、L12、复合菌株ZL共5个处理，在室温、15℃、5℃下自然发酵60 d后进行营养成分、发酵品质、微生物数量的测定。最终结果表明：温度对天然牧草青贮过程有十分显著的影响，随着温度的降低,干物质、乳酸、乙酸含量、大肠杆菌数量有下降趋势，而可溶性碳水化合物、酸性洗涤纤维含量、乳酸菌数量有上升趋势。5℃下Z906处理组的干物质、粗蛋白质含量均最高，pH值最低，乳酸含量最高，未产生丁酸，氨态氮含量最低。V-Score评分等级为良好，排名第一，得分为93.07，青贮品质最优。综上所述，在北方较冷地区对天然草青贮，可添加Z906菌株的应用效果最好。

关键词: 天然牧草, 耐低温乳酸菌, 青贮, 发酵品质