同/异型乳酸菌对青贮玉米开窖后品质及微生物的影响

Corn silage fermentation quality and microbial populations as influenced by adding homo-and hetero-fermentative bacteria after silos opened

该研究旨在分析添加不同发酵类型的乳酸菌处理对开窖后玉米(Zea mays L.)青贮发酵品质、微生物数量及有氧稳定性的影响,为生产实践提供参考。设计4个添加乳酸菌玉米青贮处理:CK处理(不加任何菌剂);T处理(同型发酵乳酸菌):Lactobacillus plantarum和Pediococcus acidilactici复合添加,添加量为1∶1,1×105 cfu/g;Y处理(异型发酵乳酸菌):Lactobacillus buchneri,添加量为1×105 cfu/g;TY处理(同型+异型发酵乳酸菌):Lactobacillus plantarum、Pediococcus acidilactici和Lactobacillus buchneri复合添加,添加量为1∶1∶1,1×105 cfu/g。发酵期为60 d,检测开窖后各处理第0、48、96、144、192、240 h发酵品质及微生物的变化,应用隶属函数法对玉米青贮发酵品质及微生物数量进行综合评判。结果表明Y和TY处理的有氧稳定时间显著高于其余处理(63.87~64.67 h,P<0.05),分别达到195.58和196.21 h,且乙酸质量分数始终显著高于CK和T处理(P<0.05)。T处理pH值始终显著低于其余处理(P<0.05),且乳酸质量分数始终显著高于CK和Y处理(P<0.05)。Y处理WSC(water soluble carbohydrate)质量分数始终显著高于其余处理(P<0.05),霉菌数量始终显著低于其余处理(P<0.05)。CK处理的NH3-N质量分数,好氧细菌数量及CO2产量始终显著高于其余处理(P<0.05)。开窖时间与各处理的CO2产量、乳酸菌和酵母菌数量分别满足Allometric1,Exp Dec1和Logistic非线性关系,与霉菌和好氧细菌数量呈一元线性关系。综合评价排序:Y处理>TY处理>T处理>CK处理。因此,单一添加异型发酵乳酸菌的玉米青贮,开窖后在改善发酵品质、降低有害微生物数量、提高有氧稳定性方面均优于单一添加同型或复合添加乳酸菌的玉米青贮。

Ensiling has been known as a method to preserve the moist in crops by controlling anaerobic fermentation. If management requirements are not met, to improve silage quality, additives are often used. Inoculation of Lactobacillus in the ensiling process has been recommended in order to make good quality silage. The objective of this study was to investigate the effects of different additives of homo- and hetero-fermentative bacteria on the fermentation characteristics, microorganism content, and aerobic stability of corn （Zea mays L. cv. Xinsiyu 10） silage during aerobic conditions for silage production practice. The corn was ensiled at 4 different treatments： Control （CK） had no added inoculants; the T group （homo-fermentative bacteria）contained Lactobacillus plantarum and Pediococcus acidilactici with a ratio of 1：1,1×105cfu/g;the Y group（hetero-fermentative bacteria）contained Lactobacillus buchneri at 1×105cfu/g;and the T＋Y group（all of these homo- and hetero-fermentative bacteria） contained Lactobacillus plantarum, Pediococcus acidilactici and Lactobacillus buchneri with a ratio of 1：1：1,1×105cfu/g,and then they were fermented for 60 days.Silage samples were collected when the silos were opened for 0, 48, 96, 144, 192, and 240 h and then analyzed to determine pH value, dry matter （DM）, crude protein （CP）, neutral detergent fiber （NDF）, acid detergent fiber （ADF）, water soluble carbohydrates （WSC）, lactic acid, acetic acid, and NH3-N, and the aerobic stability was evaluated by using an online multi-channel data logger temperature recorder. Microbial populations （Lactobacillus, moulds, yeast and aerobic bacteria） in the silage were also determined. The comprehensive assessment was performed for the 4 treatments through the calculation of 12 indices by a membership function analysis. The results showed that aerobic stability time in the Y and TY treatments reached 195.58 and 196.21 h, respectively, 63.87-64.67 h longer than that in the CK and T treatments in air respectively （P〈0.05）, and acetic acid concentrations were significantly higher than that in the CK and T treatments （P〈0.05）. T treatment showed the lowest pH value among the treatments, 0.5%-15.2% lower than other treatments （P〈0.05）, and lactic acid concentrations were significantly higher than that in the CK and Y treatments （2.4%-46.5%, P〈0.05）. Y treatment had the highest water soluble carbohydrates concentrations and the lowest population of moulds among the treatments （3.5%-24.5%, 4.6%-45.2% respectively; P〈0.05）. The NH3-N concentrations and populations of aerobic bacteria in the CK were 11.1%-43.7% and 1.2%-15.1% respectively greater than that in the T, Y, and TY treatments （P〈0.05）, and CO2concentrations in CK treatment also were the highest among the treatments （P〈0.05）. Significant linear relationship existed between moulds, aerobic bacteria populations, and silos opening time; the relationships between CO2concentrations, lactic acid bacteria, yeast populations and silos opening time were best described by Allometric Ⅰ, ExpDec Ⅰ, and Logistic equation respectively. Comprehensive evaluation was as follows： Y 〉TY〉T〉CK. Therefore, corn silage with silage addition of hetero-fermentative bacteria was better than adding silage homo-fermentative bacteria or mixed biological inoculant containing homo- and hetero-fermentative bacteria in enhancing silage fermentation quality, reducing the number of harmful microbes, and prolonging aerobic stability during the silos opening time.