Fermentation characteristics of elephant grass silages with macaúba cake

ABSTRACT. The elephant grass presents problems during the fermentation of the ensiled material, being necessary use of additives. This study aimed to evaluate the population of yeast and filamentous fungi, enterobacterias, contents of acetic and butyric acids and ethanol production, in elephant grass silages added with different levels of macaúba cake at opening times. This was a 3 x 6 factorial completely randomized experimental design, with three inclusion levels of the macaúba cake (0, 10 and 20%) and six opening times (1, 5, 10, 20, 40 and 60 days after ensiling), with four replications. For all the studied variables, there was a difference in the interaction among levels and times, and an increasing linear behavior only for the contents of acetic acid, for the other variables, the behavior was quadratic. The elephant grass silages produced acetic acid, which in turn inhibited the production of yeast and filamentous fungi. There was a small development of enterobacterias only in the first opening times, and low production of butyric acid and ethanol, which indicated a material with good fermentative characteristics. The macaúba cake contributed to improve the anaerobic fermentation process, but it was not as expressive for the parameters evaluated in this work.

摘要。象草（elephant grass）在青贮原料发酵过程中存在问题，需添加添加剂。本研究旨在评估添加不同水平马卡乌巴饼（macaúba cake）的象草青贮饲料在不同开封时间下的酵母与丝状真菌种群数量、肠杆菌（Enterobacteriaceae）含量、乙酸与丁酸含量以及乙醇生成量。本试验采用3×6完全随机析因试验设计，设置3个马卡乌巴饼添加水平（0%、10%、20%）与6个开封时间点（青贮后1、5、10、20、40、60 d），每组设置4次重复。所有观测变量均显示添加水平与开封时间间存在交互效应，仅乙酸含量随因素变化呈线性递增趋势，其余变量均呈二次曲线变化趋势。象草青贮饲料可产生乙酸，进而抑制酵母与丝状真菌的增殖。仅在初始开封时段检测到少量肠杆菌增殖，且丁酸与乙醇生成量较低，表明该青贮原料具备优良的发酵特性。马卡乌巴饼可改善厌氧发酵过程，但对本研究中评估的各项参数的提升效果并不显著。