| The aim of this study is to evaluate the effects of adding acetic acid, molasses, lactic acid bacteria and their combinations on the fermentation qualities and aerobic stability of mixed silages of oat (Avena sativa L) and alfalfa(Medicago sativa L), oat and common vetch(Vicia sativa L) during ensiling.The significance of this study was to provide a theoretical support for high quality silage modulation. The study was divided into two parts:1. Effects of adding different levels of acetic acid on fermentation quality and aerobic stability of mixed silages1.1. Effects of adding different levels of acetic acid on fermentation quality and aerobic stability of mixed silages of oat and alfalfaThe objective of this study was to evaluate the effects of adding acetic acid on the fermentation qualities and aerobic stability of mixed silage of oat and alfalfa(7:3). The treatments were as follows:control (CA) and three treatments of different acetic acid addition ratios (0.3%,0.4%,0.5% of fresh weight). Based on the result, adding acetic acid significantly (P<0.05)decreased the pH value of mixed silage, and the pH values of 0.4% and 0.5% acetic acid addition silages were significantly(P<0.05) lower than that of 0.3% acetic acid addition silages. Lactic acid (LA) contents of all acetic acid addition silages were significantly (P<0.05) higher than that of control after 60 days of ensiling, however, there was no significant (P>0.05) difference among all acetic acid silages. Acetic acid addition significantly (P<0.05) decreased the ratio of ammonia nitrogen/total nitrogen (AN/TN), and there was a decline (P>0.05) with the increase of acetic acid addition. Water soluble carbohydrate (WSC) contents of all acetic acid adding silages were significantly (P<0.05) higher than that of the control, and 0.4% acetic acid addition silages showed highest WSC content. The contents of LA and WSC decreased generally during aerobic exposition process, all acetic acid treated silages showed significantly (P<0.05) higher LA and WSC than control, and the silage adding with 0.4% acetic acid was always kept the highest lactic acid content. From the above results it was suggested that 0.4% acetic acid addition is appropriate.1.2.Effects of adding different levels of acetic acid on fermentation quality and aerobic stability of mixed silages of oat and common vetchThe aim to this study is to evaluate the effects of adding acetic acid on the fermentation qualities and aerobic stability of mixed silage of oat and common vetch(7:3). The treatments were as follows:control (CA) and three treatments of different acetic acid addition ratios (0.3%,0.4%,0.5% of fresh weight). The results showed adding acetic acid significantly (P<0.05)decreased the pH value of mixed silage, Lactic acid content had no significant change, and 0.4% acetic acid addition silages showed lowest pH and highest LA content. WSC content declined (P>0.05) with the increase of acetic acid addition. Acetic acid addition significantly (P<0.05) decreased the ratio of ammonia nitrogen/total nitrogen (AN/TN), and 0.4% acetic acid addition silages showed lowest AN/TN.During aerobic exposure, the pH and AN/TN of all additive treatments increased more slowly than the control, the LA and WSC decreased more slowly. Additives treatments had better aerobic stability.2. Effects of adding different levels of composite additive on fermentation quality and aerobic stability of mixed silages2.1. Effects of acetic acid and molasses or lactic acid bacteria combination on fermentation quality and aerobic stability of mixed silage of oat and alfalfaIt was researched that effects of adding acetic acid and molasses or lactic acid bacteria combination on fermentation quality and aerobic stability of mixed silages of oat and alfalfa in this study. The treatments were as follows:Control (C),0.4% acetic acid (0.4A),0.4% acetic acid+4% molasses (A+M) and 0.4% acetic acid+0.6ml lactic acid bacterial suspension (A+LAB). The results showed that the A+M and A+LAB treatments had significantly (P<0.05) lower pH and AN/TN than the control and 0.4A treatments, and had significantly (P<0.05) higher WSC and lactic acid content. Before 10 days aerobic exposure, the values of pH and AN/TN of the combination additions treatments were significantly (P<0.05) lower than the control and 0.4A treatments. The lactic acid contents of addition treatments were significantly (P<0.05) higher than the control. Form the above results it was suggested the combined addition treatments improved fermentation quality and aerobic stability of silage, the difference between groups was not significant (P>0.05).2.2. Effects of acetic acid and molasses or lactic acid bacteria combination on fermentation quality and aerobic stability of mixed silage of oat and common vetchIt was researched that effects of adding acetic acid and molasses or lactic acid bacteria combination on fermentation quality and aerobic stability of mixed silages of oat and common vetch in this study. The treatments were as follows:Control (C),0.4% acetic acid (0.4A),0.4% acetic acid+4% molasses (A+M) and 0.4% acetic acid+0.6ml lactic acid bacterial suspension (A+LAB). The results were as follows:either added acetic acid alone or combined with molasses, lactic acid bacteria were significantly (P<0.05) reduced the pH and the AN/TN values (P<0.05), the LA/AA and WSC content of A+M and A+LAB were significantly (P<0.05) higher than the 0.4A treatment. The pH and LA of combined addition treatments in the whole aerobic exposure stage did not change significantly (P>0.05), the AN/TN value was significantly lower than control group (P<0.05), the WSC showed A+M>A+LAB>0.4A(P<0.05). Compared with separate add acetic acid, the composite additive can improve the mixing quality of silage fermentation. |
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