苜蓿青贮优势菌种筛选及应用效果

本试验旨在筛选自然发酵苜蓿青贮的优势菌种,应用于高水分苜蓿青贮的调制,研究不同微生物及组合对高水分苜蓿青贮品质的影响。试验先调制自然发酵苜蓿,青贮30 d后,从中筛选优势菌种并进行鉴定。根据优势菌种筛选结果,组合了9组发酵菌种用于苜蓿青贮的调制,分别为:以植物乳杆菌与乳酸片球菌为发酵菌种,活菌数比例分别为1∶1、1∶2和2∶1,编号为1、2、3组;以植物乳杆菌、枯草芽孢杆菌和乳酸片球菌为发酵菌种,活菌数比例分别为2∶1∶1、1∶1∶1和4∶1∶1,编号为4、5、6组;以植物乳杆菌、解淀粉芽孢杆菌和乳酸片球菌为发酵菌种,活菌数比例分别为2∶1∶1、1∶1∶1和4∶1∶1,编号为7、8、9组;以不加任何菌种的自然苜蓿青贮作为对照。每组3个重复,发酵60 d后,对苜蓿青贮进行感官评定,并测定氨态氮/总氮(NH3-N/TN)、总酸含量和pH。结果表明:用MRS、LB和NA 3种培养基从自然发酵苜蓿青贮中筛选到微生物菌种31株,对其中18株进行了分子鉴定,主要菌种为植物乳杆菌9株、乳酸片球菌1株、粪肠球菌2株、各种芽孢杆菌6株。感官评分结果表明乳酸菌(植物乳杆菌和乳酸片球菌)比例大的各组评分等级显著高于对照组和添加了添加枯草芽孢杆菌的各组(P<0.05)。对于NH3-N/TN、总酸含量和pH等指标,乳酸菌比例较低的2、5、8和对照组与其余各组差异显著(P<0.05)。综上所述,植物乳杆菌和乳酸片球菌是苜蓿青贮主要菌种,用于苜蓿青贮有利于青贮品质的提高。枯草芽孢杆菌会影响苜蓿青贮的气味,解淀粉芽孢杆菌为菌种会改善苜蓿青贮风味,但比例太高会增加NH3-N含量。

Screening and Application Effects of Dominant Strains of Alfalfa Silage

The purpose of this experiment was to screen the dominant strains from alfalfa silage by natural fermentation and apply them to the processing of alfalfa silage,to study their effects on the quality of alfalfa silage.The alfalfa silage was processed,and after 30 days of silage,the dominant strains of alfalfa silage were screened and identified.According to the screening results of dominant strains,9 groups of fermentation strains were combined for the processing of alfalfa silage.The ratios of Lactobacillus plantarum to Staphylococcus lactis were 1:1,1:2 and 2:1,numbered groups 1,2 and 3;the ratios of Lactobacillus plantarum,Bacillus subtilis and Staphylococcus lactis were 2:1:1,1:1:1 and 4:1:1,numbered groups 4,5 and 6;and the ratios of Lactobacillus plantarum,Bacillus amylolytica and Staphylococcus lactis were 2:1:1,1:1:1 and 4:1:1,numbered groups 7,8 and 9,respectively.The natural fermentation group without any strains was used as the control.Each group repeated three times.After 60 days of fermentation,the alfalfa silage was sensory evaluated,and the ammoniacal nitrogen/total nitrogen(NH3-N/TN),total acids content and pH were determined.The results showed that 31 strains were screened from natural fermented alfalfa by MRS,LB and NA mediums.And 18 strains of them were identified.The main strains were Lactobacillus plantarum,1 strain was Staphylococcus lactis,2 strains were Enterococcus faecalis and 6 strains were Bacillus.The sensory score of the groups with large proportion of lactic acid bacteria was significantly higher than that of the control group and the groups added Bacillus subtilis(P<0.05).The NH3-N/TN,total acid content and pH of groups 2,5,8 which with lower proportion of lactic acid bacteria and control group were significantly different from other groups(P<0.05).It is concluded that Lactobacillus plantarum and Staphylococcus lactis can improve the quality of alfalfa silage.Bacillus subtilis can affect the odor of alfalfa silage.Bacillus amylolytica can improve the flavor of alfalfa silage,but high proportion will increase the content of ammonia nitrogen.