2种玉米青贮饲料青贮过程中主要微生物的变化规律研究

旨在研究玉米青贮过程中各主要微生物的数量变化及变化趋势.做去棒揉丝和带穗切段瓶制青贮,取青贮前玉米青贮原料及在装瓶后第0.5、1、2、3、4、5、6、7、9、11、13、15、20、25、30、35、40、45、50天的青贮样品,用无菌水浸泡,然后用选择性培养基培养其中的主要微生物,包括乳酸菌、酵母菌和霉菌,最后进行计数.结果表明,在玉米青贮密封后60 d内,水分含量变化很小.pH在第2天下降到4以下,然后稳定在3.5左右,带穗切段玉米青贮pH低于去棒揉丝玉米青贮.乳酸菌数量剧增,在第6、7天时达到最高峰,为109数量级,之后数量缓慢下降,于第15～20天时稳定在107数量级,去棒揉丝玉米青贮的乳酸菌数量在第7天达到最高峰,带穗切段玉米青贮则在第6天出现最高峰,其稍高于去棒揉丝玉米青贮.酵母菌在青贮初期数量有些波动,出现最高峰到达107数量级后数量随时间的延长而减少,去棒揉丝玉米青贮时酵母菌数量迅速下降,第40天后没有再检测到酵母菌的存在,而带穗切段玉米在青贮12 h之内数量迅速增加,之后缓慢下降,第50天后没有再检测到酵母菌的存在.霉菌因密封后氧气缺乏而数量很快减少,最晚在第11天左右便检测不到,去棒揉丝玉米青贮中霉菌数量下降较迅速,第4天之后便检测不到霉菌存在,而带穗切段玉米青贮则比较平缓,直到第11天之后便检测不到霉菌存在.综上所述,在玉米青贮过程中主要微生物随时间大致呈现逐步减少的趋势;对玉米秸秆进行纵切揉丝处理有利于玉米青贮饲料的制作.

Study on the Major Microorganism Changes during the Silage Processing of Two Kinds of Corn Silage

The aim of this study was to observe the number of major microorganisms and change trends during the corn silage processing.The corn silage in bottles was made by crosscutting of corn and rubbing stalk,the raw materials of corn silage were got and the silage samples at 0.5,1,2,3,4,5,6,7,9,11,13,15,20,25,30,35,40,45 and 50 days during silage processing were collected,the samples with aseptic water were soaked,and then the main microorganisms(lactic acid bacteria,yeast and mold) were cultured with selective culture medium.The results showed that the moisture content changed very little during the 60 days after the corn silage sealed.pH reduced to <4 at the 2nd day and then stayed at about 3.5.pH of corn silage was lower than that of rubbing stalk silage.The number of lactic acid bacteria increased rapidly and reached to the peak of 109 orders of magnitude at the 6th or 7th day,and later declined slowly and stabled at 107 orders of magnitude at 15th-20th day.The number of lactic acid bacteria of corn silage with a peak at 6th day was higher than that of the rubbing stalk silage with a peak at 7th day.The number of yeast had fluctuations initially and reached the peak to 107 orders of magnitude,then reduced with the treating time prolonged.The number of yeast of rubbing stalk silage reduced rapidly and disappeared after the 40th day.But the number of yeast of corn silage increased within 12 hours at the beginning of silage and then reduced slowly,finally disappeared after the 50th day.The number of mold reduced sharply because of the shortage of oxygen after sealed,and it was not found after 11th day.The number of mold of rubbing stalk silage reduced sharply and no mold was found after 4th day,while the number of mold of corn silage reduced slowly and no mold was found after 11th day.In the process of corn silage,the number of major microorganisms decreased gradually with the treating time prolonged;rubbing was beneficial to make the corn silage.