| In this study, three tests were conducted to evaluate the ensiling feasibility of mixed silage of sweet potato vines, distilled grains and rice straw.The first test was conducted to study the nutrient content, fermentation quality of different mixed ratio silage of sweet potato vines, distilled grains and rice straw, so as to acquire the optimal proportion. Based on this, further evalution was conducted to study the effect of additives (corn and lactic acid bacteria) and delayed ensiling on the nutrient content, fermentation quality of mixed silage.In experiment1, the nutrient content, fermentation quality of different mixed ratio silage of sweet potato vines, distilled grains and rice straw was studied. Five treatments included control group (C):100%fresh sweet potato vines, wilted group (W):100%sweet potato vines that natural drying for2d,40%group (S):40%fresh sweet potato vines+40%distilled grains+20%rice straw,55%group (F):55%fresh sweet potato vines+25%distilled grains+20%rice straw,70%group (Q):70%fresh sweet potato vines+10%distilled grains+20%rice straw. Chopped forage mixed together and ensiled immediately in sextuplicate1-L laboratory silos, stored at room temperature for60d. The results showed that: compared with that of C group, the sensory evalution of the other four groups were higher, the DM, CP, and LA (lactic acid) content of W group were significantly higher than that of C group (P<0.01), while NH3-N/TN, PA,(propionic acid), BA (butyric acid) content and pH value of W group were significantly lower (P<0.01). Compared with that of C group and W group, the DM, NDF, ADF, LA content of three mixed groups were significant higher (P<0.01), while the CP, Ash, NH3-N/TN, PA content and pH value were significantly lower (P<0.01). Along with the increase of the share of sweet potato vines in mixed silage, the DM content was significantly lower, while the CP content was significantly lower (P<0.05), the NH3-N/TN, PA content were significantly higher (P<0.01). Compared with that of fresh forage, the DM and CP loss of C group and W groups were higer than the mixed group, in fact, the DM and CP loss of the S group was the least. Comprehensive of sensory evaluation, nutrient composition and fermentation quality, silage of sweet potato vines, distilled grains and rice straw mixed at a ratio of40:40:20based on fresh matter (the moisture content was about65%) was the optimal proportion.In experiment2, the effect of different additives on the nutrient content, fermentation quality of the mixed silage of sweet potato vines, distilled grains and rice straw was evaluated. Based on controlled experimental design, four treatments included control group (D):40%fresh sweet potato vines+40%distilled grains+20%rice straw, no any additive involved, corn- group (Y), lactic acid bacteria-group (L) and corn+lactic acid bacteria-group (YL) were added the corn, lactic acid bacteria, and combination of the two on the basis of the D group respectively, the additive amount of corn was according to the WSC content of silage meeted4%, while the lactic acid bacteria meeted105CFU/g, each treatment had six replicates. All the mixed material was filled in1L silage bottles respectively, stored at room temperature for60d. At the same time, the ensiling quality of wrapped silage mixed with fresh sweet potato vines, distillered grains and rice straw was studied. Based on the corn-group, each package was about50kg, a total of36packages were produced. The results showed that: compared with that of D group, Added corn and lactic acid bacteria improved the sensory evalution of silage. the CP content of Y, L, YL group were significantly higher (P<0.01), while the NH3-N/TN, AA, PA content were significantly lower (P<0.01). the DM, CP, LA content of Y group silage were significantly higher than that of D group, while the NDF, ADF content of L group were significantly lower than that of D group (P<0.01). the DM content of YL group was significantly higher than that of the other two groups (P<0.01), while the NH3-N/TN, AA content and pH value of YL group was significantly lower (P<0.01). The sensory evalution of wrapped silage mixed with fresh sweet potato vines, distillered grains and rice straw at a ratio of40:40:20was excellent, pH value was3.98, the DM and CP content were35.05%,10.21%respectively. So the effect of adding the corn in the mixed silage was better than that of lactic acid bacteria. Adding the corn and lactic acid bacteria together in the mixed silage was the best.In experiment3, the effect of delayed ensiling on nutrient content, fermentation quality and aerobic stability of the mixed silage of sweet potato vines, distilled grains and rice straw was studied. Based on one-factor experimental design, three treatments included DO group that ensiled immediately, D24group that exposured to air for24h before ensiling, while D48group exposured to air for48h before ensiling, each treatment had six replicates. All the mixed forage was filled in1L silage bottles at the corresponding time respectively, stored at room temperature for60d. The results showed that:compared with DO group, with the increase of the delayed ensiling time, the sensory score and fermentation quality score decreased, the DM, CP, WSC, LA, AA content were significantly lower (P<0.01), while the NDF, ADF, ADL, NH3-N/TN, PA, BA content and pH value were significantly higher (P<0.01). The DM and CP loss of D24group were9.05%,14.14%respectively, while that of D48group were20.58%and36.63%.(4) With the increase of the aerobic exposure time, the DM, WSC, LA content of three groups were significantly lower (P<0.01), while the pH value was significantly higher (P<0.01). after exposing to air for38h,76h,50h, the DO, D24, D48group were detected the maximum temperature,1.23℃and1.20℃,1.02℃higher than the room temperature respectively. In conclusion, when the delay time increased and aerobic intervention, the water soluble carbohydrate degradated accelerately and promoted secondary fermentation, decreased the silage quality.Above all, sweet potato vines was ensilied directly or wilted before ensiling could not be a good silage, while distillered grains and rice straw addition improved fermentation quality, decreased the loss of DM, CP. Along with the increase of the share of sweet potato vines in mixed silage, the NH3-N/TN, BA content were significantly higher, so silage of fresh sweet potato vines, distilled grains and rice straw mixed at a ratio of40:40:20based on fresh matter was the best. Adding the corn and lactic acid bacteria in the mixed silage were beneficial to the lactic acid fermentation and suppressed the butyric acid fermentation, increased the DM, CP, LA content of silage. The effect of adding the corn in the mixed silage was better than that of lactic acid bacteria. Delayed ensiling caused butyric acid fermentation and decreased the ensiling quality, when the delay time increased and aerobic intervention, the water soluble carbohydrate degradated accelerately and promoted secondary fermentation. The quality of wrapped silage mixed with fresh sweet potato vines, distillered grains and rice straw at a ratio of40:40:20based on fresh matter was excellent, it might be a new approach to the comprehensive utilization of sweet potato vines, distillered grains and rice straw. |
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