Study On The Mixed Silage Of Crops Straw And Grass In Tibet

The Tibetan plateau is regarded as the Earth’s third pole and the highest unique territorial unit in the world, thus, its climate and natural environment are inherently extreme and instable. The cold and arid continental climates and short growing seasons are considered to be the most important limiting factors for forage production. The shortage of forage, over stocking rates and irrational grazing systems, resulted in sheep and yaks been caught in the vicious cycle of "glutting in summer, fatness in autumn, thinness in winter, weakness in spring". The objective of this study was to improve nutritive value of straws and to provide year-round fodder and avoid forage shortage during winter. The main results are shown as follows:1The investigation of nutrition components of crop straws and grassesThe aim of this experiment was to evaluate chemical compositions and nutritive value of crop straws (hullessbarley, wheat and oat straw) and two locally adapted grasses (perennial ryegrass and tall fescue). Crop straw showed lower nutritive value with lower water soluble carbohydrate (WSC) and crude protein (CP), but higher dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents than grasses. These straws are too low in WSC and high in DM for extensive fermentation to produce well-preserved silage, and straws and grasses may be complementary because grasses are high in WSC and moisture contents, low in NDF and ADF contents. In order to enlarge the forage resource, it was hypothesized that ensiling crop straws with grasses could improve the fermentation and nutritive value.2Studies on improving the fermentation quality and nutritive value of hullessbarley straw silage2.1Fermentation quality of hullessbarley Straw in mixture with two locally adapted grasses in Tibet The suitability of two locally adapted grasses was tested for inclusion in straw-grass silages on the hypothesis that the grasses would provide the fermentable carbohydrate for lactic acid bacteria during ensiling. The optimum straw-grass ratio was screened by inclusion different proportions of (0,20,40,60%of fresh weight) perennial ryegrass or tall fescue with hullessbarley straw. The inclusion of perennial ryegrass significantly (P<0.05) increased the contents of LA and WSC, significantly (P＜0.05) decreased the pH value and DM content. The AN/TN slightly (P>0.05) decrease in mixed silages compare with hullessbarley straw alone silages, and small amounts of BA and PA were detected in all silages. Ensiling hullessbarley straw with tall fescue significantly increased (P<0.05) the contents of LA and total VFAs, and significantly (P<0.05) decreased the pH and AN/TN, which were lowest in60%tall fescue inclusion silages. From the maximize use of straw, it was suggested that40%perennial ryegrass or60%tall fescue inclusion was proper for the further study to improve the fermentation quality of hullessbarley straw.2.2Fermentation and nutritive quality of mixed silages of hullessbarley straw and grass treated with different levels of molassesThe effect of adding molasses (0,3,4or5%of fresh weight) on the fermentation quality of mixed silages of hullessbarley straw and perennial ryegrass (6:4) during ensiling was assessed. Molasses addition faster and greatly enhanced LA production and pH value decline during the first14days. Molasses addition silages showed higher (P<0.05) LA/AA, LA and WSC content, and lower (P<0.05) pH value and AN/TN than these of silages without molasses. After60days ensiling, silages added with molasses have higher CP, lower NDF and ADF content, but there were no significant difference(P>0.05) in in vitro digestibility. These results indicated that molasses addition level over3%could effectively improve the fermentation and nutitive quality of mixed silages. The results of adding different ratios of molasses (0,3%,4%or5%of fresh weight) to mixed silage of hullessbarley straw and tall fescue (6:4) was as follows:the pH value and AN/TN were decreased as the molasses adding rates increased. During the whole ensiling,5%molasses addtion silages showed highest LA/AA and WSC content, and higher LA content than control. After60days ensiling, the CP content increased with molasses addition rates, but molasses addition silages showed lower NDF and ADF content than control. The above results indicated that adding5%molasses to mixed silages of hullessbarley straw and tall fescue was better than others.2.3The effect of cornzyme on the fermentation and nutritive quality of mixed silages of hullessbarley straw and grassTwo experiments were conducted to investigate the effect of cornzyme on the fermentation and nutritive quality of mixed silage of hullessbarley straw and two locally adapted grasses was assessed. There are four different cornzyme addition ratios (0,1.5,2.0or2.5ml/kg of fresh weight). Cornzyme addition significantly improved the fermentation quality of mixed silages of hullessbarley straw and perennial ryegrass, indicated by LA rapid accumulation, lower pH value, butyric acid and AN/TN. The pH value of silages adding with2.0and2.5ml/kg cornzyme attained4.0, and maintained to the end of ensiling, which inhibited the production of BA and PA. AN/TN in cornzyme addition silages were half of that in control, but WSC content were double of that in control. The contents of CP were higher and NDF was lower in cornzyme addition silages. From results of the present study, it was suggested that2.0ml/kg addition was effective for improving the fermentation quality of mixed ensilage of hulless barley straw and perennial ryegrass. The mixed silage of hullessbarley straw and tall fescue adding with cornzyme showed higher LA content, and lower pH value, AA, PA content during the ensiling. After60days ensiling, cornzyme addition silages showed higher WSC and CP content, but lower NDF and ADF content. After30days ensiling, the fermentation quality were worsen, indicated by LA decline and higher pH value, the value of AN/TN were higher than100g/kg TN.2.4Ensiling characteristics of mixed silages of hullessbarley straw and grass added with WHDGThe experiment was carried out to investigate the effect of WHDG inclusion on the fermentation quality of mixed silages of hullessbarley straw and perennial ryegrass. The inclusion ratios of WHDG was at0,10%,20%and30%, and others were mixture of Hullessbarley straw and perennial ryegrass (6:4). WHDG inclusion not only inhibited the activity of aerobic bacteria, but also faster and greatly enhanced LA production and pH value decline, which restricted the utilization of WSC by undesirable bacteria and decreased the loss of WSC, leaving more residual WSC in silages. Chemical compositions content of the WHDG treated silages showed that CP content were significantly higher than that of control. But after30days ensiling, all silages showed some putrescent, indicated by higher AN/TN and pH value. The effect of adding WHDG on the fermentation quality of mixed silage of hullessbarley straw and tall fescue during ensiling was assessed. WHDG addition significantly improved the fermentation quality of mixed silages, indicated by sharply accumulation of LA (P＜0.05), faster decline of pH value, lower BA and AN/TN (P＜0.05) as compared with control. These results indicated that WHDG addition not only effectively inhibited the activity of aerobic bacteria, but also speeded-up and greatly enhance LA production and pH reduction. WHDG addition inhibited the utilization of WSC by undesirable bacteria and reduced the loss of WSC, leaving more residual WSC for lactic acid bacteria. WHDG-containing silages showed higher protein content and lower NDF and ADF content than control. From results of the present study, it was concluded that20%WHDG addition was effective for improving the fermentation quality of mixed ensilage of hulless barley straw and tall fescue.3Studies on improving the fermentation quality and nutritive value of mixed silage of wheat straw and grass by adding WHDG in TibetIn order to further improve the fermentation and nutritive quality of mixed silage, wheat straw and perennial ryegrass (tall fescue) were completely mixed and added with WHDG at different ratios (0,10,20,30%of fresh weight). These silos were opened after7,14,30or60days of ensiling, and their fermentation and nutritive quality was analyzed. The addition of WHDG significantly decreased (P＜0.05) pH value and AN/TN, and increased (P＜0.05) LA content, Little BA and PA were found in WHDG addition silages. The silages adding with20%or30%WHDG showed higher LA and LA/AA, and lower pH value, which were below4.20along with the whole ensiling. Adding WHDG improved the fermentation quality of mixed silage of wheat straw and tall fescue. The LA content in WHDG addition silage were fourfold that in control, WHDG addition speeded-up the pH decline, and inhibited the activity of aerobic bacteria, so WHDG additional silages showed lower BA, PA content and AN/TN. The addition of WHDG to mixed silages resulted in an increase in CP contents, and decrease in NDF and ADF content. In conclusion, the incorporation of WHDG increased the fermentation and nutritive quality of mixed silages of wheat straw and grass, and this effect were more marked when inclusion rate was beyond20%.4Studies on improving the fermentation quality and nutritive value of mixed silage of oat straw and grass by adding WHDG in TibetThe objectives of this study were to determine the effect of WHDG addition on the fermentation and nutritive quality of mixed silages of oat straw and perennial ryegrass. WHDG was added at0,10,20,30%of fresh weight respectively. All WHDG additional treatments promoted a more efficient fermentation, as indicated by sharply accumulation of LA, faster decline of pH, lower BA, VFAs and AN/TN than control, WHDG addition not only increased CP content, but also decreased NDF and ADF content, resulting in higher digestibility. LA content decreased and pH value increased with WHDG addition rates increased from10%to30%, this possibility attribute to higher WHDG addition inhibited the activity of lactic acid bacteria and aerobic bacteria. It was suggested that the adding10%WHDG could improve the fermentation quality and nutritive value of mixed silages of oat straw and perennial ryegrass. Mixtures of oat straw and tall fescue were ensiled with WHDG, which was added at four levels (0,10,20or30%of fresh weight). Based on the results, after14days of ensiling, the LA content in WHDG addition silages was fivefold of that in control, the pH value of WHDG addition silages was below4.20, and pH value of20%and30%WHDG addition silages were about3.90, and keep this level until to the end of ensiling. WHDG addition significantly improved the fermentation quality of mixed silage, which was well indicated by significantly lower (P＜0.05) pH, AN/TN, BA and PA content and significantly higher (P＜0.05) DM and LA content than control. WHDG addition silages showed higher CP contents, and lower NDF and ADF content. From the present study, it can be concluded that the fermentation and nutritive quality of mixed silage was considerably improved by20%or more WHDG addition.