甜高粱与苜蓿不同比例对混合青贮营养成分及发酵品质的影响

Effects of different proportions of sweet sorghum and alfalfa on nutrient composition and fermentation quality of mixed silage

试验旨在研究甜高粱与苜蓿不同混合比例对混合青贮营养成分及发酵品质的影响。各组苜蓿占比分别为0(T1组)、20%(T2组)、40%(T3组)、60%(T4组)、80%(T5组)和100%(T6组),每组4个重复,青贮60 d后,检测各组青贮饲料的感官、营养成分、发酵参数等指标。结果表明,T3组~T5组的青贮饲料酸香味较浓,呈淡黄色,茎叶结构保持良好,等级达到优质。T6组青贮饲料的pH值显著高于T1组、T3组、T4组(P<0.05);T5组和T6组青贮饲料的氨态氮/总氮的比值显著高于其他组(P<0.05),T3组、T4组氨态氮/总氮的比值显著高于T1组和T2组(P<0.05)。T2组丙酸含量显著高于T3组、T4组、T6组(P<0.05),仅有T6组检出丁酸,其余组均未检出丁酸,T5组和T6组的乳酸含量显著低于其他组(P<0.05)。T4组、T5组、T6组青贮饲料的有机物、干物质含量显著高于T1组和T2组(P<0.05);T4组、T5组、T6组的中性洗涤纤维和酸性洗涤纤维含量显著低于T1组和T2组(P<0.05),T5组、T6组的粗纤维含量显著高于T1组和T2组(P<0.05),T2~T6组的粗蛋白含量均显著高于T1组(P<0.05),T3~T6组的可溶性碳水化合物含量显著低于T1组和T2组(P<0.05)。研究表明,苜蓿与甜高粱混合青贮可以改善青贮营养价值和发酵品质,且苜蓿占60%时,青贮效果较好。

The experiment was conducted to study the effects of different mixing ratios of sweet sorghum and alfalfa on the nutrient composition and fermentation quality of mixed silage.The proportion of alfalfa in each group was 0(T1 group),20%(T2 group),40%(T3 group),60%(T4 group),80%(T5 group)and 100%(T6 group),and four replicates were set in each group.After 60 days of silage,the sensory,nutrient composition and fermentation parameters of silage in each group were detected.The results showed that the silage treated with T3~T5 groups had strong acid flavor,light yellow color,good stem and leaf structure,and high grade.The pH value of mixed alfalfa and sweet sorghum silage in T6 group was significantly higher than that in T1 group,T3 group,and T4 group(P<0.05).Ammonia nitrogen/total nitrogen in T5 group and T6 group was significantly higher than that in other groups(P<0.05),and T3 group and T4 group were significantly higher than that in T1 group and T2 group(P<0.05).The propionic acid content in T1 group was significantly higher than that in other groups(P<0.05),and the propionic acid content in T2 group was significantly higher than that in T3 group,T4 group,and T6 group(P<0.05).Butyric acid was detected only in group T6 mixed silage,and no butyric acid was detected in other groups.The lactic acid content of T5 group and T6 group was significantly lower than that of the other groups(P<0.05).The organic matter and dry matter of silage in T4 group,T5 group and T6 group were significantly higher than those in T1 group and T2 group(P<0.05).The contentrations of neutral detergent fiber and acid detergent fiber in T4 group,T5 group and T6 group were significantly lower than those in T1 group and T2 group(P<0.05).The crude fiber content in T5 group and T6 group was significantly higher than that in T1 group and T2 group(P<0.05).The crude protein content in T2~T6 groups was significantly higher than that in T1 group(P<0.05).The content of soluble carbohydrate in T3~T6 groups was significantly lower than that in T1 group and T2 group(P<0.05).The study indicates that alfalfa and sweet sorghum mixed silage can improve the nutritional value and fermentation quality of silage,and the silage effect is the best when alfalfa accounts for 60%.