| The study was mainly to evaluate the effect of different silage additives on fermentation quality and aerobic stability of mixed silages of hullessbarley straw and perennial ryegrass. Different levels of sorbic acid, ethanol and propionic acid were added separately to explore the effects of mixed silage, in the further evaluate the effect of inhibitors and molasses, cornzyme respectively, and supply theoretical evidences for the development of silage additives in Tibet.1. Effect of sorbic acid on fermentation quality and aerobic stability of mixed silages of hullessbarley straw and perennial ryegrass.The experiment was carried out to evaluate the influence of adding different levels of propionic acid (0.10%,0.15%,0.20%) on fermentation quality and aerobic stability of mixed silages. The results showed that adding sorbic acid decreased butyric acid (BA), ammonia nitrogen/total nitrogen (AN/TN) and increased water soluble carbohydrate (WSC) of silage and effectively improved the silage fermentation quality after30-days of ensilaging.The pH of0.15%and0.20%addition was always significantly (P<0.05) lower than control, and the DM was significantly (P<0.05) higher than control. Compared with the control, the sorbic acid reduced the decline rate of lactic acid (LA) and WSC and decreased the rising rate of BA and AN/TN. And the contents of LA and WSC increased with higher propionic acid addition. In summary, more than0.15%addition can effectively inhibited the activities of aerobic microorganisms, reduced corruption and improved aerobic stability.during silages exposed to air.2. Effect of ethanol on fermentation quality and aerobic stability of mixed silages of hullessbarley straw and perennial ryegrass.The effect of adding different levels of ethanol (1.5%,2.5%,3.5%) on fermentation quality and aerobic stability of mixed silages was studied. The results showed that LA, LA/AA and WSC were higher (P>0.05) or significantly higher (P<0.05) than control. The B A and AN/TN were significantly (P<0.05) lower than control and1.5%thanol addition.The pH of control was significantly increased and thanol additions increased more slowly than control during aerobic stage of silage. The reduction rate of WSC, DM and LA were slower than control, moreover, the contents increased with higher ethanol addition. The control and1.5%ethanol addition were significantly (P<0.05) higer than2.5%and3.5%ethanol.The AN/TN and BA of each group increased during aerobic exposure. Considering,2.5%ethanol addition improved fermentation quality and aerobic stability of mixed silages.3. Effect of propionic acid on fermentation quality and aerobic stability of mixed silages of hullessbarley straw and perennial ryegrass.The experiment was carried out to evaluate the influence of adding different levels of propionic acid (0.3%,0.4%,0.5%) on fermentation quality and aerobic stability of mixed silages. The results showed that the differences among pH, LA and DM were not significantly (P>0.05), LA and WSC of0.4%and0.5%propionic acid were significantly (P<0.05) higher than control, and the AN/TN and BA were significantly lower than control and0.3%propionic acid addition. The pH value of0.4and0.5%propionic acid addition increased more slowly than control and0.3%propionic acid addition during aerobic exposure. The DM, LA and WSC decreased gradually during exposure, moreover, the contents increased with higher propionic acid addition. And AN/TN and BA of each group increased during aerobic exposure, but0.4%and0.5%propionic acid addition were significantly (P<0.05) higher than control and0.3%addtion. The results indicated that adding over0.4%propioinc acid improved fermentation quality and aerobic stability of mixed silages.4. Effect of combining addition of ethanol, sorbic or propionic acid with molasses on fermentation quality and aerobic stability of mixed silages.The experiment was carried out to evaluate the effects of combining addition of ethanol, sorbic or propionic acid with molasses on fermentation quality and aerobic stability of mixed silages. There were five treatments, conrol, M (molasses), SM (0.15%sorbic acid+molasses), EM (2.5%ehanol+molasses), PAM (0.4%propionic acid+molasses). The results showed that either added molasses alone or sorbic acid, ethanol and propionic acid combination were significantly (P<0.05) increased LA and WSC and decreased VFAs and AN/TN. The LA and WSC of PAM and SM were ignificantly (P<0.05) higher than EM.The pH of control was significantly increased and the LA and WSC were significantly (P<0.05) decreased. The combination additions changed more slowly than control during aerobic stage of silage. The pH value of PAM decreased significangtly (P<0.05) lower than other treatments. Compared with the control, the LA and WSC were significantly(P<0.05) higher, the BA and AN/TN were significantly (P<0.05) lower. In summary, the combined addition improved fermentation quality and aerobic stability of silage which added propionic+molasses combination worked best.5. Effect of combining addition of ethanol, sorbic or propionic acid with cornzyme on fermentation quality and aerobic stability of mixed silages.The effect of combining addition of ethanol, sorbic or propionic acid with cornzyme on fermentation quality and aerobic stability of mixed silages was studied. There were five treatments, conrol, ME (cornzyme), SME (0.15%sorbic acid+cornzyme), EME (2.5%ehanol+cornzyme), PAME (0.4%propionic acid+cornzyme). The results showed that added cornzyme alone significantly (P<0.05) decreased AA and increased LA/AA. The combining addition significantly (P<0.05) decreased pH, BA and AN/TN, and significantly (P<0.05) increased residual WSC.The pH of control was significantly increased and the LA and WSC were significantly (P<0.05) decreased. Compared with control, the combined addition had lower pH, AN/TN and BA. To sum up, combining addition of ethanol, sorbic or propionic acid with cornzyme effectively improved fermentation quality and aerobic stability of silage, but the differences among each group were not significant (P>0.05). |
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