【作者】 张静；

【导师】 邵涛；

【作者基本信息】 南京农业大学 ， 草业科学， 2008， 硕士

【摘要】 本研究的目的就是评价好氧性微生物抑制剂对意大利黑麦草发酵品质及有氧稳定性的影响,通过添加不同水平的丙酸和己酸,分析青贮30天的发酵品质及在有氧期间青贮饲料的化学成分变化,比较两种添加剂不同添加水平对青贮饲料的pH、干物质、乳酸、挥发性有机酸含量,筛选出各自的最适添加量,并进一步探讨这两种添加剂最适浓度分别与乳酸菌组合添加后对多花黑麦草青贮发酵品质和有氧稳定性的影响。试验以多花黑麦草作为青贮原料,采用小型塑料青贮罐（100ml）在实验室条件下模拟生产实践进行青贮,30天后全部打开测定发酵品质的各项指标及水溶性碳水化合物含量,并在8天的有氧期间（0,2,4,6,8天）,测定发酵品质及碳水化合物的动态变化,筛选出最佳的添加水平。将筛选所得最适浓度（丙酸0.5%;己酸0.2%）,以及选取的参照浓度（丙酸0.4%;己酸0.15%）,分别与乳酸菌组合构成四个组合添加处理,与这四个浓度单独添加处理组和对照组进行比较。硕究表明:（1）低浓度丙酸对青贮发酵品质的影响不显著（P＞0.05）,但是随添加浓度增加,具有良好改善趋势;在有氧阶段各时间检测点,丙酸浓度处理组pH、干物质（DM）、氨态氮/总氮（NH₃-N/TN）明显低于同一天中所测对照组,而乳酸和碳水化合物（WSC）则显著升高（P＜0.05）,在一个相对较长的时间范围内保持青贮饲料的原有发酵品质。（2）不同己酸浓度处理组青贮饲料在整个有氧测定阶段表现出较好的有氧稳定性,但是其青贮发酵品质没有得到改善,有些情况下可能还会使发酵品质下降。（3）不管是丙酸单独还是复合添加,以及己酸的复合添加都明显降低了青贮饲料乙酸、丁酸、氨态氮/总氮（NH₃-N/TN）含量（P＜0.05）,显著增加WSC和乳酸含量（P＜0.05）,较好改善了青贮发酵品质;在整个有氧暴露阶段,丙酸和己酸各处理组中乳酸和WSC含量下降变化幅度显著缓于对照组（P＜0.05）,且丁酸含量极少甚至没有,尽管较高的丙酸和乙酸含量使得总挥发性脂肪酸（VFAs）含量很高（P＜0.05）,但它们是青贮饲料有氧稳定性提高的主要因子。（4）与对照组相比,乳酸菌处理组中乳酸含量虽然显著升高（P＜0.05）,但乳酸:乙酸远低于3:1,同时丙酸和丁酸含量也分别增加了96.6%,169.4%,未达优质青贮饲料标准;有氧阶段,对照组和乳酸菌处理组中所测定分析的各营养成分含量变化趋势基本一致（P＞0.05）,到第8天,乳酸:乙酸都低于2:1;WSC含量分别降低了46.1%,46.8%;氨态氮/总氮（NH₃-N/TN）含量分别升高了88.2%,92.6%,表现出很差的有氧稳定性。综上所述,添加丙酸和己酸后可明显降低干物质有氧损失,延缓二次发酵,提高青贮有氧稳定性,且添加水平越高,作用效果越好。如果青贮条件较好,添加适宜高浓度丙酸可以改善青贮发酵品质。从改善青贮发酵品质和提高有氧稳定性两个方面综合来看,丙酸和己酸与乳酸菌的组合添加后的叠加效应优于单独添加效果。更多还原

【Abstract】 The purpose of this study is to evaluate the effect of adding propionic acid and caproic acid on the fermentation quality and aerobic stability of Italian ryegrass silage, and the proper rate of adding propionic acid and caproic acid on the fermentation quality and aerobic stability of Italian Ryegrass (Lolium multiflorum Lam.) silages were determined. In the further, the effect of proper rate of adding propionic acid and caproic acid alone or with lactic acid bacteria on the fermentation quality and aerobic stability were estimated on 30th days or during aerobic stages. The pH, dry matter, lactic acid and water soluble carbohryate were analysed, and the proper adding rate was seleckted. the dynamic changes in fermentation were in further studied with the selected adding rate with lactic acid bacteria treatments during aerobic stages.The fresh Italian ryegrass was harvested at the heading stages, and then chopped and packed into small scale experiment silos (100 ml) immediately. The all silos were opened on the 30th day after ensiling and were analyzed the fermentation quality. The dynamic change of fermentation quality of adding propionic acid (0.3%, 0.4%, 0.5%) and caproic acid (0.1%, 0.15%, 0.2%, 0.25%) were analyzed on 0, 2, 4, 6, 8 days of aerobic exposure. Forthemore, the proper rate levels (Propionic acid-0.5%; Caproic acid-0.2%) and tow comparative levels (Propionic acid-0.4%; Caproic acid-0.15%) to alone or combined with lactic acid inoculation, and compared with Control and LAB-treaded. After 30 days of ensiling, opened the silos and three silos per treatment were adopted in different times during exposure days to study aerobic stability.The study result showed: (1) When compared with Control-treaded silage, the silages alonelv treated with Propionic acid and Caproic acid at each level all had no effects on fermentation of silages after 30 days of ensiling(P>0.05), but by the rate was higher, the quality was tend to become better. Propionic acid-treated silages had better aerobic stability than Control-treaded silage, because the Control-treaded silage showed a higher pH, DM, Ammonia-N (P<0.05), and lower content of lactic acid and WSC(P<0.05) in different times during aerobic exposure days. ( 2 ) Caproic acid -treaded silages had better aerobic stability than Control-treaded silage in whole aerobic detected period, but the feremetation quality were’t improved, even became worse. (3 ) Regardless of Propionic acid alonely or jointly accession and all Caproic acid combined treated silages had lower content of acetic acid, butiryc acid and Ammonia-N(.P<0.05), higher content of lactic acid and WSC(P<0.05), they were preferably ameliorating the quality of silages. The change of depressed extent on lactic acid and WSC in all Propionic acid and Caproic acid-treated silages were notability slower compared with control silage, and there were only a few butiryc acid or no. Because of higher content of propionic acid and caproic acid, the total VFAs were also higher in them, but these tow acids could improve aerobic stability. ( 4 ) Compared with Control-treaded silage, the quality of LAB-treaded silage was worse, although the lactic acid content of it was markedly improved, but the rate of lactic acid : acetic acid was far lower than 3:1, and the content of propionic acid and caproic acid were increased 96.6 %, 169.4%. The tend of changes of all detected nutrition components in Control and LAB-treaded silages were almost identical(P>0.05), up to 8th day, the rate of lactic acid : acetic acid were under 2:1; WSC reduced 46.1% and 46.8%; Ammonia-N increased 88.2% and 92.6%.By the above analysis, we can see that, appending propionic acid and caproic acid can recede the aerobic loss, delay second fermentation, enhance aerobic stability, and the higher accession level, the better effect. If the condition was well, condign and high level propionic acid could improve fermentation quality. From improving fermentation quality and enhancing aerobic stability to see, when propionic acid and caproic acid combined with microbial inoculation, the geminate effect remarkable better than witch were alone accession.更多还原