豆粕添加和发酵时间对甜象草青贮营养品质与细菌多样性的影响

为研究添加豆粕和不同发酵时间对甜象草青贮品质和细菌多样性的影响,以甜象草为研究对象,设置无豆粕添加甜象草青贮(LSL饲料)和添加20%豆粕甜象草青贮(HSL饲料),在青贮袋中发酵10 d、30 d和60 d,分别对发酵料进行感官评价,测定pH值、含水量、养分含量和菌群结构。结果表明:两组饲料在发酵期间的感官评价均为优质。发酵30 d,感官评价已达到优良等级,粗蛋白质、氨态氮/总氮、乳酸和乙酸含量均显著增加(P<0.05),60 d有所降低;发酵期间HSL的粗蛋白质含量显著高于LSL(P<0.05)。发酵30 d,厚壁菌门和乳杆菌属在两组饲料中的相对丰度最高,60 d有所降低,其在HSL饲料中的相对丰度高于LSL饲料,变形菌门和肠杆菌属在HSL饲料中的相对丰度低于LSL。综上,添加20%豆粕能有效改善甜象草的青贮品质,促进乳杆菌属细菌生长,抑制有害细菌增殖。推荐甜象草青贮饲料的适宜发酵时间为30 d。

Effects of soybean meal addition and fermentation time on nutritional quality and bacterial diversity of Pennisetum purpureum silage

To study the effect of adding soybean meal silage and different fermentation time on quality and bacterial diversity of Pennisetum purpureum, P. purpureum was used as the research object, control design was adopted in the experiment, with no soybean meal added P. purpureum silage (LSL feed) and 20% soybean meal added P. purpureum silage (HSL feed). Fermented in silage bag for 10 d, 30 d and 60 d, the sensory evaluation, pH value, water content, nutrient content and flora structure were measured. The results showed that the sensory evaluation of both groups of feed during fermentation was high quality. After 30 days fermentation, the sensory evaluation had reached the excellent grade, and the contents of crude protein, ammonia nitrogen/total nitrogen, lactic acid and acetic acid increased significantly (P<0.05). The contents of nutrients decreased at 60 days; the crude protein content in HSL was significantly higher (P<0.05) than that in LSL during silage. After 30 days fermentation, the abundance values of Firmicutes and Lactobacillus in both groups were the highest, but decreased at 60 days, their abundance in HSL feed were higher than those in LSL feed, while the abundance values of Proteobacteria and Enterobacter in HSL feed were lower than those in LSL feed. In conclusion, the addition of 20% soybean meal could effectively improve the silage quality of P. purpureum, promote the growth of Lactobacillus and inhibit the proliferation of harmful bacteria. The suitable silage time of P. purpureum was 30 days.