添加不同乳酸菌对青贮玉米和青贮黑麦草发酵品质、有氧稳定性的影响

目的] 研究添加乳酸片球菌（PA）与短乳杆菌（LB）对青贮玉米和青贮黑麦草发酵品质、有氧稳定性的影响。方法] 选用从发酵TMR中分离出的乳酸片球菌和短乳杆菌,设置对照组（添加自来水）、PA组（添加乳酸片球菌）、LB组（添加短乳杆菌）和PA+LB组（乳酸片球菌和短乳杆菌联合添加）4个处理组,进行全株玉米和黑麦草的青贮发酵试验,发酵时长为30 d。青贮饲料开封后测定pH值、乳酸含量、乙酸含量、乳酸菌和酵母菌数量等反映青贮饲料品质的指标,同时进行有氧稳定性试验。结果] 青贮玉米在30 d开封后,4个处理组的pH值和乳酸含量差异不显著（P>0.05）;LB组和PA+LB组乙酸含量显著（P<0.05）高于对照组,PA组和PA+LB组乳酸菌数量显著（P<0.05）高于对照组;有氧稳定性试验中,PA+LB组青贮玉米5 d后腐败,其余试验组均在2.5 d以内腐败。青贮黑麦草在30 d开封后,添加乳酸菌的各试验组pH值和乙醇含量均显著（P<0.05）低于对照组,乳酸含量均显著（P<0.05）高于对照组,PA组乳酸含量最高;有氧稳定性试验中,除对照组外,添加乳酸菌的各试验组青贮黑麦草均在7 d后腐败,PA+LB组乳酸含量最高,乙酸含量显著（P<0.05）低于LB组。结论] 向青贮玉米中单独添加乳酸菌,对于青贮品质和有氧稳定性无明显作用;联合添加乳酸菌对于青贮玉米的发酵品质无明显改善,但对其有氧稳定性有一定的改善作用。向青贮黑麦草中添加乳酸菌对发酵品质和有氧稳定性有改善作用,添加乳酸片球菌改善发酵品质作用最佳,联合添加乳酸菌既可以改善青贮黑麦草的有氧稳定性还能提高发酵品质。

Effects of Adding Different Lactic Acid Bacteria on Fermentative Quality and Aerobic Stability of Corn and Ryegrass Silage

Objective]To investigate the effects of adding Pediococcus acidilactici(P.acidilactici)and Lactobacillus brevis(L.brevis)on fermentative quality and aerobic stability of corn and ryegrass silage.Method]Experimental strains of P.acidilactici and L.brevis were isolated from fermented TMR.Thirty-day-long silage fermentation trials using whole plant corn and ryegrass were conducted by setting four treatment groups,including control group(adding tap water),PA group(adding P.acidilactici),LB group(adding L.brevis)and PA+LB group(simultaneously adding P.acidilactici and L.brevis).After the sealed silage was opened,the indicators associated with silage quality,such as pH value,lactic acid content,acetic acid content,and the number of lactic acid bacteria and yeasts were determined,and the aerobic stability test was carried out.Result]For corn silage,after a 30-day-long fermentation,no significant(P>0.05)differences in pH value and lactic acid content among the four treatment groups were observed;the contents of acetic acid in LB group and PA+LB group were significantly(P<0.05)higher than that in control group,and the numbers of lactic acid bacteria in PA group and PA+LB group were significantly(P<0.05)higher than that in control group;in the aerobic stability test,the spoilage of corn silage in PA+LB group was observed after 5 days of opening,and those in the other groups were observed within 2.5 days after opening.For ryegrass silage,after a 30-day-long fermentation,the pH values and ethanol contents in the experimental groups added with lactic acid bacteria were significantly (P<0.05) lower than those in control group, and the lactic acid content was significantly (P<0.05) higher than that in control group with the highest value in PA group;in the aerobic stability test, except for control group, the spoilage of ryegrass silage in the experimental groups added with lactic acid bacteria was observed after 7 days of opening, the lactic acid content in PA + LB group was the highest, and the acetic acid content in PA + LB group was significantly (P<0.05) lower than that in LB group. Conclusion] Single addition of P. acidilactici or L. brevis has no significant effect on quality and aerobic stability of corn silage, and the combinative addition of P. acidilactici and L. brevis has no significant improvement in fermentative quality of corn silage, but improved its aerobic stability. Addition of lactic acid bacteria improves the fermentative quality and aerobic stability of ryegrass silage, and addition of P. acidilactici has the best performance in improving the fermentative quality. Furthermore, the combinative addition of P. acidilactici and L. brevis not only improves aerobic stability of ryegrass silage, but also improve its fermentative quality.