苜蓿与直穗鹅观草混贮发酵品质研究

以苜蓿(Medicago sativa)与直穗鹅观草（Roegneria turczaninovi）为原料，按不同比例混贮，通过分析发酵品质和营养成分，优化混合青贮比例。结果表明，苜蓿青贮后干物质（DM）和中性洗涤纤维（NDF）含量增加，粗蛋白（CP）、 酸性洗涤纤维（ADF）、可溶性碳水化合物（WSC）含量降低，直穗鹅观草青贮后DM、NDF、CP及ADF含量增加，粗脂肪（EE）和WSC降低；混贮处理CP和Ca含量显著高于直穗鹅观草单贮，而显著低于苜蓿单贮，DM、NDF、ADF含量显著低于直穗鹅观草单贮；随直穗鹅观草在混贮比例中的提高，pH值呈降低趋势，混贮中乳酸占总酸含量居于两种牧草单贮之间，苜蓿与直穗鹅观草3∶7混贮乙酸含量占总酸含量显著高于其他处理（P＜0.05），为33.9%，混贮处理丁酸产生较少；苜蓿与直穗鹅观草混贮氨态氮占总氮含量显著低于苜蓿单贮（P＜0.05），且显著高于直穗鹅观草单贮（P＜0.05）；青贮后各处理乳酸菌数达到106 cfu/g（以鲜物质为基础），较青贮前提高，各混贮处理乳酸菌和霉菌数高于两种牧草单贮；直穗鹅观草单贮发酵品质评分为97分，且氨态氮含量较低，为最佳处理。

The fermentation quality of mixed silage of Medicago sativa and Roegneria turczaninovii

The different proportions of Medicago sativa and Roegneria turczaninovii were ensiled to optimize the proportion of mixed silage by measuring the nutrition constituent, which was used to estimate fermentation quality. The results of this study showed that the silage increased the content of DM and NDF and decreased the CP, ADF, WSC of alfalfa products, and that the silage increased the content of DM, NDF, CP and ADF, and decreased the EE and WSC of R. turczaninovii. The CP and Ca content of mixed silage was significantly higher than R. turczaninovii silage and lower than alfalfa silage, and the content of DM, NDF, ADF was significantly lower than R. turczaninovii silage. As the proportion of R. turczaninovii increased in mixed silage, the pH decreased, and the content of lactic acid accounting for total acid in mixed silage was between two single silages. The content of acetic acid accounting for total acid in the mixed treatment of alfalfa and R. turczaninovii (3∶7) was 33.9%, and was significantly higher than other treatments(P＜0.05), and butyric acid in mixed treatment was little. The content of ammonium nitrogen accounting for total nitrogen in mixed silage was significantly lower than alfalfa silage(P＜0.05)，and was significantly higher than R. turczaninovii silage(P＜0.05). Counts of lactic acid bacteria in all treatments after ensiling reached 106 cfu/g（FM）, and was higher than non ensiling, and counts of lactic acid bacteria and mould in mixed treatments was high than two single silage. The score of fermentation quality of R. turczaninovii silage was 97, and the content of ammonium nitrogen was low; therefore, R. turczaninovii silage was optimal treatment.