| In this experiment, corn,alfalfa and Roegneria turczaninovii (Drob.) Nevski were chosen to determine the characteristics of microbial flora during single and mixed silage fermentation from 2009 to 2010, and main conclusions are as follows:(1) Lactic acid bacteria, aerobic bacteria, coliform bacteria, yeast and mold were found in silage materials, the process of ensiling and the period finishing ensiling, and counts of these microorganisms in different periods varies intensely. Counts of adnascent lactic acid bacteria on silage materials was too much less than harmful microorganisms. Counts of adnascent lactic acid bacteria on different silage materials was less than 105 cfu/g FM besides corn, and counts of adnascent lactic acid bacteria on corn was far more than alfalfa and Roegneria turczaninovii (Drob.) Nevski. Counts of adnascent lactic acid bacteria on alfalfa of the same crop and different cultivars had no difference. Counts of adnascent lactic acid bacteria on alfalfa of different crops had no difference, but counts of adnascent harmful microorganisms on the second crop was far more than the first crop. As declining of moisture content, counts of adnascent lactic acid bacteria on alfalfa increased gradually, and counts of adnascent harmful microorganisms decreased.(2) Compared with silage materials, all kinds of microorganisms increased greatly after ensiling. On the whole, during ensiling, counts of all kinds of microorganisms experienced a process of increasing slowly, increasing acutely, declining after maximuming, finally stabilizing on a low level. Influenced by characteristics of materials, fermentation conditions and additives, counts of microorganisms in some silage experienced fluctuation two or three times. Time when different microorganisms began to increase acutely and maximum may be the same or different, and the maximum of different microorganisms was different. Characteristics and proportion of materials in mixed silage influenced the counts, maximum and time of maximizing of all kinds of microorganisms. In some silage, counts of microorganisms experienced dramatic growth in the later period of fermentation. During fermentation, maximum of lactic acid bacteria were 109.50～1010.38 cfu/g FM, and the maximum usually appeared after ensiling 15 20 days.(3) In alfalfa (Gannong No.3) silage , counts of different kinds of microorganisms in the second crop was overall more than the first crop, and time of maximum in the second crop was earlier , and the maximum was smaller. Overall, counts of different kinds of microorganisms in alfalfa silage was the highest, Roegneria turczaninovii (Drob.) Nevski silage was the next, and corn silage was the least. As declining of moisture content in alfalfa, counts of all kinds of microorganisms decreased gradually. Adding molasses in silage can promote the multiplication of lactic acid bacteria. In natural fermentation process, counts of lactic acid bacteria had no advantages and amounts to the counts of aerobic bacteria, yeast and mold. In the process of ensiling, counts of coliform bacteria was far less than other microorganisms.(4) Fifty-four lactic acid bacteria strains were isolated from silage materials, the initial and later fermentation stage. These strains belonged to five genuses and ten species, including P. pentosaceus, L. plantarum, E. faecium, P. acidilactici, E. hirae, E. Mundtii, W. confusa, Le. mesenteroides subsp. Mesenteroides, E. durans and L. curvatus, and counts of P. pentosaceus, L. plantarum and E. faecium was significant.(5) Five lactic acid bacteria strains GI7, GI11, GI24, GI44 and GI62 were screened for their quicker acid-production rate, and L. plantarum GI62 was the most suitable strains used for additive for its quicker acid-production rate and speed of growth. Using lactic acid bacteria additives can increase the counts of lactic acid bacteria in alfalfa silage, lower the pH value, and L. plantarum GI62+P. pentosaceus GI11+P. acidilactici GI7 was the most optimal one. |
PDF Full Text Request