添加乳酸菌制剂和丙酸对全株玉米全混合日粮青贮发酵品质和有氧稳定性的影响

The Effects of Lactic Acid Bacteria and Propionic Acid on the Fermentation Quality and Aerobic Stability of Total Mixed Ration Silages Prepared with Whole-crop Corn in Tibet

为评价乳酸菌制剂和丙酸对西藏地区全株玉米全混合日粮(TMR)发酵品质和有氧稳定性的影响。试验设对照组、乳酸菌制剂和丙酸添加组3个处理。全混合日粮青贮45d后全部开封取样,测定其发酵品质,并分别在有氧暴露第6、9和12天取样评定其有氧稳定性。每个处理组每个时间点开5个青贮窖即5个重复。结果表明,全株玉米全混合日粮干物质含量适宜、乳酸菌数量和水溶性碳水化合物含量充足,因此对照组发酵品质良好,添加乳酸菌制剂进一步改善了发酵品质,虽然丙酸一定程度上抑制了乳酸发酵,但发酵品质仍属良好。在有氧暴露阶段,对照组和乳酸菌添加组乳酸含量持续下降,pH﹑氨态氮/总氮和酵母菌数量显著上升(P<0.05)。丙酸添加组乳酸含量前9d逐渐升高,之后显著下降(P<0.05),pH基本趋于稳定,12d后降至3.75,酵母菌数目显著(P<0.05)低于其他组。综合全株玉米TMR的发酵品质和有氧稳定性,添加乳酸菌制剂改善了全株玉米TMR的发酵品质但没有提高其有氧稳定性,添加丙酸尽管一定程度抑制了乳酸发酵,但明显提高了发酵全混合日粮的有氧稳定性。

The objective of this study was to evaluate the effects of lactic acid bacteria and propionic acid on the fermentation quality and aerobic stability of total mixed ration(TMR)silage prepared with whole-crop corn in Tibet.The treatments were as follow:control(no additives),inoculated lactic acid bacteria with 1g·kg-1 or propionic acid adding with 0.4% on fresh matter basis of TMR.All silos per treatment were opened after 45 days of ensiling,5silos per treatment were used for fermentation quality determination,and then sampled on 6,9and 12 days after exposure to air which were subjected to aerobic stability evaluation,5replicates for each treatment at every time point.The results showed that the fermentation quality of control was good as indicated bythe appropriate dry matter content,abundance of lactic acid bacteria count and water soluble carbohydrate content.The addition of lactic acid bacteria further improved fermentation quality.Although the addition of propionic acid inhibited the lactic acid fermentation,the fermentation quality was also good.During aerobic exposure stage,control and lactic acid bacteria addition silages showed decrease in lactic acid content,increase in pH,ammonia nitrogen/total nitrogen and the number of yeast.Lactic acid content in propionic acid silages increased during the first 9days of aerobic exposure,and then significantly(P<0.05)decreased.The pH and the number of yeast in propionic acid silages were significantly(P<0.05)lower than those of control and lactic acid bacteria addition silages.Adding lactic acid bacteria improved fermentation quality but did not affect the aerobic stability;adding propionic acid inhibited lactic acid production during fermentation,while delayed aerobic deterioration of TMR silages,thus adding propionic acid improved the aerobic stability of whole-crop corn total mixed ration silage.