不同水分及乳酸菌处理对玉米秸秆黄贮发酵指标和体外干物质消失率的影响

Effects of different treatments of moisture and lactobacillus on the fermentation quality of straw silage and the loss rate of dry matter in vitro

为了研究添加乳酸菌与否和水分含量的多少对玉米秸秆黄贮发酵品质和体外干物质消失率的影响,试验采用两因素试验设计（水分处理4×乳酸菌处理2）,其中水分处理分别为50%、55%、60%、65%,再进行乳酸菌添加和非添加处理,即乳酸菌组和对照组。通过小规模发酵法,在室温条件下保存30 d后开封,测定黄贮的感官品质、化学成分、发酵品质、微生物组成和体外干物质消失率。结果表明：与对照组相比,乳酸菌组黄贮的乳酸、有机物、粗蛋白、粗脂肪含量显著提高（P〈0.05）,pH值及耐热菌、酵母菌数、大肠杆菌数、丁酸菌数显著降低（P〈0.05）,体外干物质消失率和产气量提高;不同水分处理间秸秆黄贮的粗蛋白、粗脂肪、酸性洗涤纤维、乳酸含量及酵母菌数、大肠杆菌数、丁酸菌数差异显著（P〈0.05）,在水分为60%时粗蛋白含量最高、酸性洗涤纤维最低、酵母菌数最少,而粗脂肪和乳酸含量随水分升高而增高。说明在添加乳酸菌及水分为60%时玉米秸秆黄贮的发酵品质最好。

The aim of the present study was to investigate the effects of lactic acid bacteria addition and moisture content on fermentation quality of straw silages and disappearance rate of dry matter in vitro. A 2-factor test design（moisture treatment 4×lactic acid bacteria treatment 2） was used in the experiment, in which the moisture treatment was 50%, 55%, 60% and 65% respectively. These four kinds of moisture materials were subjected to lactic acid bacteria addition and non-addition treatment, that was, lactic acid bacteria group and the control group. By means of small scale fermentation, it was stored at room temperature for 30 days and then opened. Then the sensory quality, chemical composition, fermentation quality, microbial composition and dry matter disappearance rate in vitro were determined. The results showed that the contents of lactic acid, organic matter, crude protein and ether extract in the lactic acid bacteria group were significantly increased（P〈0.05）. The pH value, the number of heat-resistant bacteria and yeast were significantly decreased（P〈0.05）, and the disappearance rate and gas production of dry matter in vitro increased. There were significant differences in crude protein, crude fat, acid-washed fiber, lactic acid content, yeast count, coliform count and butyric acid count among different moisture treatments（P〈0.05）. When the moisture content was 60%, the crude protein content was the highest, the acid detergent fiber was the lowest, and the yeast count was the least, while the crude fat and lactic acid content increased with the increase of moisture content. The results indicated that the corn straw silage had the best fermentation quality when lactic acid bacteria and moisture content was 60%.