甜高粱与苜蓿混贮的发酵、有氧稳定性及微生物变化研究

发布时间：2018-08-08 22:03

【摘要】：苜蓿(Alfalfa)属豆科牧草,因其蛋白含量高、缓冲度高,青贮难以成功。甜高粱(Sweet sorghum)属禾本科C4植物,光合效率高、含糖量和生物产量高、耐旱耐盐碱、且抗逆性强,容易青贮。理论上讲,二者混合制作青贮可以克服各自缺陷,提高混贮饲料的能-氮平衡。因此,本试验以甜高粱与苜蓿按0:100(0%SS),20:80(20%SS),40:60(40%SS),60:40(60%SS),80:20(80%SS),100:0(100%SS)的混合比例制作的混贮饲料为材料,通过感官评定、化学和发酵品质分析、青贮菌群多样性和有氧稳定性分析,研究了混合比例与混贮品质、营养特性、菌群变化及有氧稳定性之间的关系,旨在为甜高粱与苜蓿混贮的科学利用提供实验资料。对混贮感官评定以及营养和发酵特征的研究表明,40%SS比例的混贮效果最佳,其成功率高、结构完好、气味色泽好、蛋白质含量较高。本研究共分离得到18株乳酸菌,4株鼠李糖乳杆菌,5株植物乳杆菌,3株耐久肠球菌,2株肠膜明串珠菌肠膜亚种,2株屎肠球菌,乳酸乳球菌和干酪乳杆菌各1株,其中,植物乳杆菌产酸性能好,生长速度快。不同比例甜高粱与苜蓿混贮发酵过程中pH、有机酸和主要微生物数量的研究表明,100%SS的混贮pH下降最快,在发酵的第45 d时最低;乳酸菌、乳酸(LA)、乙酸(AA)在混贮中含量随发酵时间的延长而呈上升趋势,且100%SS混贮中LA、AA含量和乳酸菌数量显著高于其它比例混贮。混贮中酵母菌、霉菌、好氧菌数量随发酵时间的延长而呈下降趋势,其中80%SS和100%SS比例的混贮中的酵母菌和霉菌分别青贮的第25 d和10 d时消失。混贮中乳酸菌多样性的PCR-DGGE分析结果表明:乳酸菌类群随混贮中甜高粱比例的增加而减少,其中20%SS、40%SS和60%SS混贮乳酸菌种类较为丰富,100%SS混贮中乳酸菌种类最少;鼠李糖乳杆菌和屎肠球菌是混贮0%SS、20%SS、40%SS、60%SS、80%SS的优势乳酸菌,肠膜明串珠菌和屎肠球菌是混贮100%SS的优势乳酸菌;100%SS与其它混贮的乳酸菌相似性最低仅为32%,0%SS与20%SS、40%SS与60%SS混贮乳酸菌群落构成一致;0%SS、20%SS、80%SS与40%SS和60%SS的混贮中乳酸菌群落的相似性为70%。混贮有氧稳定性及微生物数量的变化研究表明,甜高粱与苜蓿混贮的有氧稳定性随甜高粱比例的增加而下降,其中,苜蓿青贮有氧稳定性最好;随有氧暴露时间的延长,乳酸菌数量逐渐减少,酵母菌、霉菌和好氧菌数量则逐渐上升,pH呈上升趋势;在有氧暴露的相同时间比较,酵母菌和好氧菌的数量随甜高粱在混贮中比例的增加而显著上升,霉菌则随甜高粱比例的增加而显著减少。总之,添加少量甜高粱即可明显提高混贮成功率,且添加一定比例的甜高粱有益于提高混贮的有氧稳定性,抑制霉菌的生长。
[Abstract]:Alfalfa (Alfalfa) belongs to leguminous forage, because of its high protein content and high buffering, silage is difficult to succeed. Sweet sorghum (Sweet sorghum) belongs to Gramineae C4 plant with high photosynthetic efficiency, high sugar content and biological yield, drought and salt tolerance, strong resistance to stress and easy silage. Theoretically speaking, the mixed silage can overcome their defects and improve the energy-nitrogen balance of the mixed feed. Therefore, the mixed feed made of sweet sorghum and alfalfa at the ratio of 0: 100 (0%SS) 20: 80 (20%SS) 40: 60 (40%SS) 60: 40 (60%SS) 80: 20 (80%SS) 100: 0 (100%SS) was used as the material. The mixed proportion and the mixed storage quality were studied by sensory evaluation, chemical and fermentation quality analysis, silage community diversity and aerobic stability analysis. The relationship among nutritional characteristics, microbial population changes and aerobic stability is intended to provide experimental data for the scientific utilization of sweet sorghum and alfalfa mixed storage. The sensory evaluation, nutrition and fermentation characteristics of mixed storage showed that the mixed storage effect was the best, with high success rate, good structure, good smell and color, and high protein content. In this study, 18 strains of lactic acid bacteria, 4 strains of Lactobacillus rhamnoides, 5 strains of Lactobacillus plantarum, 3 strains of durable Enterococcus, 2 strains of Enterococcus faecium, 1 strain of Lactococcus lactis and 1 strain of Lactobacillus casei were isolated. Lactobacillus plantarum has good acid production and fast growth rate. The study of pH, organic acid and the number of main microorganism in mixed fermentation of sweet sorghum and alfalfa with different proportion showed that the pH of mixed storage of 100SS was the fastest, and the lowest was at the 45th day of fermentation, the lactic acid bacteria, lactic acid bacteria, The content of lactate (LA), acetate (AA) increased with the increase of fermentation time, and the content of lactic acid bacteria in the mixed storage of 100%SS were significantly higher than those of other mixed storage. The number of yeast, mold and aerobic bacteria decreased with the increase of fermentation time, and the ratio of 80%SS and 100%SS disappeared at the 25th and 10th day of silage, respectively. The results of PCR-DGGE analysis on the diversity of lactic acid bacteria in mixed storage showed that the species of lactic acid bacteria decreased with the increase of the proportion of sweet sorghum in mixed storage, among which 20SS 40SS and 60%SS mixed storage lactic acid bacteria were abundant in 100SS mixed storage. Lactobacillus rhamnoides and Enterococcus faecium are the predominant lactic acid bacteria in the mixture of 0 SS1 20 and 20 10% SS60% SS60 and 10% SS 80SS. Streptococcus enteromembranum and Enterococcus faecium were the dominant lactic acid bacteria mixed with other lactic acid bacteria. The lowest similarity of lactic acid bacteria between SS and 20SS40SS and 60%SS was the lowest. The similarity of lactic acid bacteria community between SS and 40%SS and 60%SS was 700.The similarity of lactic acid bacteria community between SS and 40%SS and 60%SS was 700.The results showed that the lactic acid bacteria community was similar to the lactic acid bacteria community in the lactic acid bacteria community of the mixed storage of Lactic acid bacteria (Lactic acid bacteria 100SS) and other lactic acid bacteria (lactic acid bacteria). The study on aerobic stability and microbial quantity of mixed storage showed that the aerobic stability of mixed storage of sweet sorghum and alfalfa decreased with the increase of the proportion of sweet sorghum, among which, the aerobic stability of alfalfa silage was the best, and with the prolongation of aerobic exposure time, the aerobic stability of alfalfa silage decreased with the increase of the proportion of sweet sorghum. The number of lactic acid bacteria gradually decreased, the number of yeast, mold and aerobic bacteria increased gradually, and the number of yeast and aerobic bacteria increased significantly with the increase of the proportion of sweet sorghum in mixed storage at the same time of aerobic exposure. The mildew decreased significantly with the increase of sweet sorghum ratio. In short, adding a small amount of sweet sorghum can obviously improve the success rate of mixed storage, and adding a certain proportion of sweet sorghum is beneficial to improve the aerobic stability of mixed storage and inhibit the growth of mold.
【学位授予单位】：塔里木大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S816.53

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