| This study was carried out to evaluate the effects of adding perennial ryegrass, tall fescue, molasses, wet brewers’grains on the fermentation qualities of alfalfa. There are six experiments in this study.Experiment1:Effect of different combination ratio of alfalfa and perennial ryegrass on fermentation quality. Chopped perennial ryegrass and alfalfa were combined in ratios of0%:100%,80%:20%,70%:30%,60%:40%,100%:0%(denoted Control, PA20, PA30, PA40, and P100respectively), and the silos were opened after7,14,30and60days of ensiling and the fermentation quality were analyzed. Based on the results, pH value of the PA20, PA30, PA40and P100treatments were lower or significantly lower (p<0.05) than the control treatment, while the DM and WSC contents were higher or significantly higher (p<0.05) than the control treatment in the first30days. During the whole fermentation period, the contents of acetic acid and total volatile fatty acids of PA20, PA30, PA40and P100treatments were significantly lower (p<0.05) than the control treatment, while LA/AA value were significantly higher (p<0.05) than the control treatment. The combination of alfalfa and perennial ryegrass could stimulate the dominant fermentation of lactic acid bacteria. During the early stage of ensiling, AN/TN value of the PA20, PA30, PA40and P100treatments were higher than the control treatment, which indicated that the activity of clostridia was not totally inhibited and thus the content of NH3-N was increased. The PA30treatment which was considered as the most appropriate ratio for mix, had lowest pH value, low contents of total VFA and AA and high contents of DM, LA and WSC.Experiment2:Effect of different molasses application levels on fermentation quality of alfalfa and perennial ryegrass mixed silages. The silage treatments were as follows, Control, PAM3:3%molasses, PAM4:4%molasses, PAM5:5%molasses, PAM3×W10:3%molasses+10%wet brewers’grains. The silos were opened after7,14,30and60days of ensiling and the fermentation quality were analyzed. The result showed that molasses provided the lactic acid bacteria with aboundant fermentation substrates and thus pH value significantly (p<0.05) decreased which inhibited the activity of clostridia and decreased the protein utilization. The AN/TN value of PAM3×W10treatment were lower or significantly (p<0.05) lower than those of control and other molasses treatments. Because the alcohol in the wet brewers’ grains inhibited the activity of undesired microorganisms. Adding3%molasses and10%wet brewers’ grains could decrease the pH value, AN/TN, AA and VFA contents and increase the WSC content and LA/A A value. This study suggested that PAM3×W10treatment had the best fermentation quality.Experiment3:Effect of different wet brewers’ grains application levels on fermentation quality of alfalfa and perennial ryegrass mixed silages. The silage treatments were as follows, Control, PAW10:10%wet brewers’ grains, PAW20:20%wet brewers’ grains, PAW30:30%wet brewers’ grains. The silos were opened after7,14,30and60days of ensiling and the fermentation quality were analyzed. The result showed that the pH value of the wet brewers’ grains treatments were lower or significantly (p<0.05) lower than that of control treatment. The value of pH and AN/TN decreased with the increasing wet brewers’ grains level, which indicated that wet brewers’ grains could inhibit the activity of clostridia. The content of lactic acid of the wet brewers’ grains treatments higher than that of the control treatment, while the acetic acid content lower than that of the control treatment, which indicated that wet brewers’grains could stimulate the dominant fermentation of lactic acid bacteria. The alcohol in the wet brewers’ grains inhibited the activity of microorganisms, resulting in the lower content of total volatile fatty acids of the wet brewers’grains treatments. The pH value, AN/TN, acetic acid and total volatile fatty acids of silages were declined with wet brewers’grains, while the contents of lactic acid, WSC and LA/AA increased. This experiment suggested that PAW30treatment had the best fermentation quality.Experiment4:Effect of different combination ratio of alfalfa with tall fescue on fermentation quality. Chopped tall fescue and alfalfa were combined in ratios of0%:100%,80%:20%,70%:30%,60%:40%,100%:0%(denoted Conrtrol, TA20, TA30, TA40and T100respectively), and the silos were opened after7,14,30and60days of ensiling and the fermentation quality were analyzed. Based on the result, the pH value of TA20, TA30and TA40treatment was lower or significantly (p<0.05) lower than that of control treatment during the whole ensiling period, while the pH value of T100treatment was higher than that of control treatment in the early stage of ensiling. The combination of alfalfa and tall fescue significantly (p<0.05) increased the contens of DM and WSC, which provided aboundant fermentation substrates for lactic acid bacteria, resulting in the significantly higher contents of lactic acid in the TA30and TA40treatment. The contents of acetic acid, total volatile acid and propionic acid in the TA20, TA30, TA40and T100treatment were significantly (p<0.05) lower than those of control treatment, while the AN/TN was higher or significantly (p<0.05) higher than the control treatment, which indicated that combination of alfafal and tall fescue stimulated the utilization of protein instead of inhibiting the activity of clostridia. The TA30treatment which was considered as the most appropriate ratio for mix, had higher contents of DM, lactic acid and LA/AA, lower contents of total volatile fatty acid, acetic acid and propionic acid.Experiment5:Effect of different molasses application levels on fermentation quality of alfalfa and tall fescue mixed silages. The silage treatments were as follows, Control, TAM3:3%molasses, TAM4:4%molasses, TAM5:5%molasses, TAM3×W10:3%molasses+10%wet brewers’ grains. The silos were opened after7,14,30and60days of ensiling and the fermentation quality were analyzed. Based on the result, molasses could decrease pH value, and the pH value increased with the increasing molasses level. The pH value of TAM3×W10treatment was lower or significantly (p<0.05) lower than that of TAM3, TAM4, TAM5and control treatments. The content of DM in the TAM3, TAM4, TAM5and TAM3×W10treatments was higher or significantly (p<0.05) higher than that of control treatment, which indicated that molasses could preserve the DM content. Molasses could increase or significantly (p<0.05) increase the content of WSC which stimulated the lactic acid fermentation and inhibited the activity of microorganism, resulting in the low content of total volatile fatty acids. The content of total volatile fatty acids in the TAM3×W10treatment was significantly (p<0.05) lower than that of TAM3, TAM4, TAM5and control treatments, because the activity of microorganism was inhibited by the alcohol in the wet brewers’grains. Molasses could decrease or significantly (p<0.05) decrease the AN/TN, with the lowest value in the TAM3×W10treatment, which indicated that the activity of clostridia was inhibited and decreased the protein utilization. The pH value, AN/TN, acetic acid and total volatile fatty acids of silages were declined with3%Molasses+10%wet brewers’ grains treatments, while the contents of WSC, DM and LA/AA increased. This study suggested that TAM3×W10treatment had the best fermentation quality. Experiment6:Effect of different wet brewers’ grains application levels on fermentation quality of alfalfa with tall fescue mixed silages. The silage treatments were as follows, Control, TAW10:10%wet brewers’grains, TAW20:20%wet brewers’grains, TAW30:30%wet brewers’grains. The silos were opened after7,14,30and60days of ensiling and the fermentation quality were analyzed. Based on the result, wet brewers’grains could significantly (p<0.05) decrease the pH value, and the pH value increased with the increasing wet brewers’grains level. The content of lactic acid of TAW10, TAW20and TAW30treatment was significantly (p<0.05) higher than that of control treatment, while the acetic acid content lower than that of control treatment. Wet brewers’grains significantly decreased (p<0.05) AN/TN value with the increasing wet brewers’grains level, which indicated that wet brewers’grains inhibited the activity of clostridia. The content of total volatile fatty acid of TAW10, TAW20and TAW30treatment, with the lowest content in the TAW30treatment, which indicated that the activity of some microorganisms was inhibited. The result showed that the pH value, AN/TN, acetic acid, butyric acid and total volatile fatty acids of silages were declined with wet brewers’grains, while the content of lactic acid and LA/AA increased. This experiment suggested that TAW30treatment had the best fermentation quality. |
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