添加残次苹果发酵物对稻草青贮品质及其微生物数量的影响

Effects of adding defective apple fermentation in rice straw on quality and microbial numbers of mixed silage

为了探讨添加残次苹果发酵物改善稻草的青贮品质及其适宜添加比例,该研究按残次苹果发酵物和稻草质量比为全部为稻草(Ⅰ)、1∶9(Ⅱ)、3∶7(Ⅲ)、5∶5(Ⅳ)、7∶3(Ⅴ)、9∶1(Ⅵ)混合进行青贮。青贮90 d后开封,测定青贮前后的营养成分,鉴定青贮饲料的感官品质、发酵品质以及有氧暴露情况下pH值和微生物数量的变化。结果表明,添加残次苹果发酵物显著提高青贮原料的粗蛋白(Crude Protein,CP)和可溶性碳水化合物(Water Soluble Carbohydrate,WSC)的含量(P<0.05),降低了原料的中性洗涤纤维(Neutral Detergent Fiber,NDF)和酸性洗涤纤维(Acid Detergent Fiber,ADF)的含量(P<0.05);青贮90 d天后,混合青贮饲料的乳酸(Lactate Acid,LA)、乙酸(Acetic Acid,AA)含量随着残次苹果发酵物添加量的增加而增加;处理Ⅰ的LA(0.17%)、AA(0.09%)含量显著低于其他5个处理(P<0.05),而丁酸(Butyric Acid,BA)含量、AN/TN(Ammonia Nitrogen Total Nitrogen)的比值显著高于其他5个处理(P<0.05);有氧暴露后,随着有氧暴露时间的延长,各处理的pH值、酵母菌数量、霉菌数量逐渐增多,乳酸菌数量逐渐减少;处理Ⅰ的乳酸菌数量始终显著低于其他各处理(P<0.05),酵母菌和霉菌数量始终显著高于其他各处理(P<0.05);而处理Ⅲ、Ⅳ的乳酸菌数量始终显著高于其他处理(P<0.05),酵母菌和霉菌数量始终保持较低水平。未添加残次苹果发酵物处理Ⅰ的感官评分和综合评分均为劣等,添加残次苹果发酵物的稻草青贮处理Ⅲ和处理Ⅳ的感官评分和综合评分均为优等;同时添加残次苹果发酵物增加了混贮的营养价值,改善了混贮的发酵品质。综合分析,在试验中添加残次苹果发酵物能改善稻草的青贮品质,其添比例在3∶7~5∶5之间适宜。

This study aims to fully use the defective apple as rice straw resources in Xinjiang, China. Three lactic acid bacteria in different proportion were added to the defective apple, and fermented for more than 1 month to obtain the defective apple fermentation. Then, an investigation was made to evaluate whether the addition of defective apple fermentation can improve the fermentation quality of rice straw, particularly on an appropriate addition proportion. Mixed silage was carried out according to the weight ratio of defective apple fermentation and rice straw at all in straw(Ⅰ), 1:9(Ⅱ), 3:7(Ⅲ), 5:5(Ⅳ), 7:3(Ⅴ), and 9:1(Ⅵ), and 3 replicates for each group, then they were fermented for 90 days. The pH value was measured by an acidometer, while the Dry Matter(DM) by dried at 105 ℃, Crude Protein(CP) by Kjeldahl method, Neutral Detergent Fiber(NDF), and the Acid Detergent Fiber(ADF) were determined, Water-Soluble Carbohydrates(WSC) were determined by anthrone-sulfuric acid colorimetric method, lactic acid, acetic acid, propionic acid, and butyric acid were determined by chromatographic method, and NH3-N was determined by phenol-sodium hypochlorite colorimetric method. The results showed that the addition of defective apple fermentation products improved the quality of mixed silage. The contents of CP and WSC in a rice straw increased significantly(P < 0.05). After 90 days of silage, the Lactic Acid(LA) contents from group Ⅰ to Ⅵ was 0.17%, 0.85%, 1.95%, 2.43%, 2.67%, and 2.71%. Acetic Acid(AA) contents from group Ⅰ to Ⅵ was 0.09%, 0.32%, 0.43%, 0.74%, 0.78%, and 0.85%, respectively. The contents of LA and AA increased with the increase of defective apple fermentation, and obviously lower in group Ⅰ(without defective apple fermentation) than other groups(P < 0.05). The Butyric Acid(BA) content from group Ⅰ to Ⅵ was 0.22% 0.08%, 0.05%, 0.03%, 0.09%, and 0.11%. NH3-N/TN from group Ⅰ to Ⅵ was 16.28%, 8.35%, 3.01%, 2.94%, 2.66%, and 2.58%, respectively. The BA, NH3-N/TN and p H value decreased with the increase of defective apple fermentation, where in group Ⅰ significantly higher than other groups(P < 0.05). The pH value, the number of yeasts and molds increased gradually, and the number of lactic acid bacteria decreased gradually under aerobic exposure environment, with the extension of exposure time. During the period of aerobic exposure, the number of lactic acid bacteria in group Ⅰ was always significantly lower than that in other treatments(P < 0.05), and the number of yeasts and molds was always significantly higher than that of other treatments(P < 0.05), while the number of lactic acid bacteria in groups Ⅲ and Ⅳ was always significantly higher than that in other treatments(P < 0.05), indicating that the number of yeasts and molds remained at a low level. The sensory and comprehensive scores of group Ⅰ without defective apple fermentation were inferior, and those of rice straw silage groups Ⅲ and Ⅳ added with defective apple fermentation were excellent. Comprehensive evaluation was as follows in order: Ⅳ>Ⅲ>Ⅴ>Ⅵ>Ⅱ>Ⅰ. Therefore, the silage nutritional values of the added defective apple fermentation were improved and the rice straw was softened. Comprehensive analysis results showed that the quality of rice straw silage can be improved by adding the defective apple fermentation in this experiment, and the appropriate proportion of the defective apple fermentation and the rice straw was between 3:7 and 5:5. The finding can provide a sound basis for utilization of biologicals.