【作者】 洪梅；

【导师】 刁其玉；

【作者基本信息】 中国农业科学院 ， 动物营养与饲料科学， 2011， 硕士

【摘要】 本论文从青贮窖中筛选了2株乳酸菌,通过16SrDNA的方法对其进行分子生物学鉴定,并利用青贮发酵罐全面评价这两株乳酸菌对全株玉米青贮发酵进程的影响,最后通过饲养试验研究其对奶牛生产性能的影响,旨在开发一种青贮饲料接种剂,为生产应用提供科学依据。具体包括以下三个部分:试验一响应面法优化青贮饲料乳酸菌的培养条件从青贮饲料中筛选得到2株乳酸菌,经16SrDNA的方法对其进行分子生物学鉴定,两株乳酸菌分别为植物乳杆菌(GLP01),该菌株与Gen Bank中的Lactobacillus plantarum strain KLDS(登录号:EU626013.1)相似度为98%;发酵乳杆菌(BLF01),与Gen Bank中的Lactobacillus fermentum strain 44197(登录号:DQ779203.1)相似度为99%。通过单因素试验设计研究了培养基组成(碳源、氮源)和培养条件(温度、接种量、起始pH等)对GLP01和BLF01生长繁殖的影响;采用二次响应面分析方法对其培养条件进行优化,得到生长模型以及取得该模型最优值时各因素的水平。试验结果表明,培养GLP01的最适碳源是果糖,最佳氮源是酵母粉,最佳培养条件是起始pH 5.47、培养温度35.3℃、接种量8.16%;培养BLF01的最适碳源是乳糖,最佳氮源是酵母粉,最佳培养条件是起始pH 6.5、培养温度35℃、接种量1%。试验二不同微生物接种剂对全株玉米青贮发酵品质的影响试验以蜡熟期全株玉米为原料,设4个处理组,分别为:对照组(CK)、植物乳杆菌组(G)、发酵乳杆菌组(B)以及植物乳杆菌+布氏乳杆菌组(LG),其中CK组不添加接种剂、G组添加植物乳杆菌105 cfu/gFM,B组添加发酵乳杆菌也为105 cfu/g FM,LG组添加的植物乳杆菌和布氏乳杆菌均为105 cfu/gFM。青贮饲料发酵过程中,分别于第1、3、5、7、9、12、15、30、45、60、90天开罐取样,进行青贮品质检测、化学成分分析和微生物检测。结果显示,本试验中所用的植物乳杆菌和发酵乳杆菌均能有效改变全株玉米青贮的发酵过程,即能够主导全株玉米青贮发酵。添加植物乳杆菌能够有效促进全株玉米青贮中乳酸菌的生长繁殖(P<0.05),同时抑制真菌的活动(P <0.05),从而显著降低青贮饲料的pH值(P<0.05),同时提高乳乙酸的生成比值,使得发酵进程向同型发酵转变。发酵乳杆菌也属于典型的同型发酵乳酸菌,而且产酸能力显著高于其他各组(P<0.05),其乳酸的生成量比其他组高出13.2%～46.36%;在发酵过程中,该组的pH值显著低于其他组(P<0.05),为3.68。但是,正因为发酵乳杆菌的强产酸能力,抑制了大部分乳酸菌的生长,却为可利用乳酸的酵母菌提供了有利环境。植物乳杆菌与布氏乳杆菌联合应用,能够促进乳酸菌的生长,显著降低全株玉米青贮的pH值,同时抑制真菌的生长繁殖活动。但是,该组的乳乙酸生成比值是2.01,为各组中最小,属于典型的异型发酵。试验三接种不同乳酸菌的全株玉米青贮对奶牛生产性能的影响以全株玉米为青贮原料,设3个处理组,分别为对照组、植物乳杆菌组和布氏乳杆菌组,其中对照组不添加接种剂,其他两个组添加的菌种量均为105 cfu/gFM。青贮方式为地上水泥青贮窖,两个月后开封。同时,选取21头中国荷斯坦经产奶牛,随机分成3组,研究不同处理的全株玉米青贮对泌乳牛产奶量和乳成分的影响。结果表明:以4%标准乳计,与对照组相比,植物乳杆菌组产奶量平均每日每头增加2.21 kg,布氏乳杆菌组增加0.3 kg/天/头。此外,植物乳杆菌组显著提高了乳脂率(P<0.05)。更多还原

【Abstract】 To investigate the effects of two inoculations on corn silage fermentation, microbial contents, and milk production, 2 strains of lactic acid bacteria, -identified as Lactobacillus fermentum strain 44197 and Lactobacillus plantarum strain KLDS by the method of 16SrDNA were screened from silage.Experiment 1 was conducted to optimize the culture conditions for the growth of GLP01, Lactobacillus plantarum, and BLF01, Lactobacillus fermentum. Response surface methodology (RSM) was applied for the critical medium components (carbon source, nitrogen source, initial pH, temperature and inoculum size) identified earlier by one-factor-at-a-time approach. Using this methodology, the optimal carbon source and nitrogen source of GLP01 were fructose and yeast powder. Using RSM, the optimal culture conditions of GLP01were pH 5.47, temperature 35.3℃, inoculum size 8.16%; The optimal carbon source and nitrogen source of BLF01 were lactose and yeast powder, the optimal culture conditions were pH 8.0, temperature 35℃, inoculum size 1%.Experiment 2 was designed to study effects of the two microbial inoculants on corn silage fermentation, nutritive value and microbial contents. Corn was treated with nothing(CK), or L.plantarum (G), or L.fermentum (B), or L.plantarum+L.buchneri (LG), at a final application rate of 105 cfu/g of fresh forage and ensiled in laboratory silos for 1、3、5、7、9、12、15、30、45、60、90 d. Treatment with Lactobacillus plantarum had effects on the end products of fermentation, which increased the amount of LAB (P<0.05), decreased the amount of fungus (P<0.05), and markedly decreased pH value when compared to untreated silage. Treated with L. fermentum had a higher concentration of lactic acid (6.42% vs. 5.57%) but lower acetic acid (9.08% vs. 12.68%) than untreated silage. Treating corn silage with L.plantarum+L.buchneri markedly decreased the pH value (P<0.01), and the ratio of lactic acid to acetic acid of this group was 2.01, but the group of CK, G, and B was 6.69, 9.27 and 8.05 respectively.Experiment 3 was designed to study the effect of L.plantarum and L.buchneri on milk production under field conditions. The milk production increased 2.21kg/d and 0.3kg/d-when treated with L.plantarum and L.buchneri respectively. Treated with L.plantarum and L.buchneri markedly increased the fat percentage (P<0.05).更多还原