Study On Improving Mixed Ensilage Fermentation Quality Of Wheat Straw With Perennial Ryegrass Or Tall Fescue In Tibet

This study was carried out to evaluate the fermentation quality of both the mixed silage of wheat straw with perennial ryegrass and tall fescue at different rates and the mixed silage adding cornzyme and molasses to find the optimal mixture and additives. The silos were opened on7,14,30, and45days of ensiling, separately. Three silos are used for each treatments and ensilage days.Experiment Ⅰ:Effect of different mixed ratios on fermentation quality of mixed silage.Wheat straw with perennial ryegrass and tall fescue were chopped, and mixed in ratios of80:20,60:40,40:60(fresh weight basis), denoted WP20(WT20)、WP40(WT40)、 WP60(WT60), respectively, and ensiled in laboratory vacuum silos.Part one:The fermentation quality of the mixed silage of wheat straw with perennial ryegrass. The pH value of decreased quickly during the early stage of ensiling. The values of pH were lower (P<0.05), whereas the contents of LA and WSC were higher (P<.05) than other bi-crop ratios. It showed that the fermentation was dominated by lactic acid bacteria in the WP60. The pH value of bi-crop silage did not reach below of4.2after60days of ensiling. Meanwhile, all treatments had lower content of LA and higher content of BA and AN/TN.Part two:The fermentation quality of the mixed silage of wheat straw with fescue. The pH value of bi-crop silage was still above of4.8after60days of ensiling, and lactic acid was also very low.According to general evaluation of fermentation quality of all treatments, it was suggested that the fermentation quality of wheat straw and perennial ryegrass in40:60was better than any other, which had the lowest pH value (4.55), and higher contents of LA, WSC and lower content of AN/TN.Experiment Ⅱ:Effect of adding cornzyme on fermentation quality of mixed silage.Chopped wheat straw with perennial ryegrass and tall fescue were combined in ratios of40:60, and ensiled adding cornzyme in laboratory silos. The adding rations of cornzyme were0ml kg-1,1.5ml kg-1,2.0ml kg-1,2.5ml kg-1(fresh weight basis), denoted Control, WPE-1.5(WTE-1.5), WPE-2.0(WTE-2.0), WPE-2.5(WTE-2.5) respectively.Part one:The fermentation quality of wheat straw with perennial ryegrass. The results showed that the pH value and the TVFA of WPE-2.5were significantly lower (P<0.05) than control during early stage of ensiling. It could increase more fermentation substrate adding cornzyme and inhibited the proteolysis by aerobic microorganisms in the early stage of ensiling. The bi-crop silage adding cornzyme improved the fermentation quality as compared with control after60days of ensiling. All treatments decreased significantly (P<0.05) the pH value, and increased the contents of WSC. The WPE-2.5bi-crop ration had the lowest pH (4.1), lower content of AN/TN. The pH value of WPE-1.5, WPE-2.0was close to4.2. It indicated that cellulose could improve the fermentation quality of wheat straw mixed with perennial ryegrass. Part two:The fermentation quality of wheat straw with fescue. During the whole ensiling process, the pH value of each treatment adding E, were over5.0. All treatments had low content of LA and high content of AN/TN. It showed that adding cellulose could not improve the fermentation quality of wheat straw mixed with fescue.Experiment Ⅲ:Effect of adding molasses on fermentation quality of mixed silage.Chopped wheat straw with perennial ryegrass and tall fescue were combined in ratios of40:60, and ensiled adding molasses in laboratory silos. The adding rations of cornzyme were0%,3%,4%,5%(fresh weight basis), denoted Control, WPM-3(WTM-3), WPM-4(WTM-4) and WPM-5(WTM-5) respectively.Part one:The fermentation quality of wheat straw with perennial ryegrass. The pH value of all treatments adding molasses had a quick drop, as well as a quick fall of BA and AN/TN (P<0.05) after60days of ensiling, and the pH values of WPM-3was close to4.2, with high contents of LA and residual WSC. It was suggested that the fermentation of mixed silage adding molasses was improved. Part two:The fermentation quality of wheat straw with fescue. All treatments adding molasses had higher pH value (above4.2), besides the content of BA, WSC and AN/TN, did not have significant (P<0.05) change compared with control. So, molasses had not effectively improved the fermentation quality of the mixed silage of wheat straw with fescue.