甜高粱青贮有氧暴露的稳定性及微生物变化的研究

Aerobic stability and microbial populations in sweet sorghum silages during aerobic exposure

为了更好地开发利用甜高粱青贮饲料,本研究以高糖甜高粱青贮(HSS)、低糖甜高粱青贮(LSS)和玉米青贮(MZS)为材料,研究了在有氧暴露0、5、10、15、20和25 d时干物质、水溶性碳水化合物(WSC)、pH、温度和微生物数量的变化。结果表明,在有氧暴露前期(0~5 d),与LSS和MZS比较,HSS具有较低的pH值,较高的乳酸菌含量和较高的温度;在有氧暴露的后期(15~25 d),HSS酵母菌、霉菌和好氧菌数量均显著大于LSS和MZS(P<0.05),LSS的温度和pH值显著低于HSS和MZS(P<0.05);在整个有氧过程中,WSC含量在HSS中最高,干物质含量在LSS中最高(P<0.05)。可见,在有氧暴露环境下,LSS有氧稳定性最好,酵母菌、霉菌和好氧细菌数量增加最少;HSS有氧稳定性最差,酵母菌、霉菌和好氧细菌数量增加最多;MZS有氧稳定性和好氧性微生物数量居中。本研究结果提示,HSS在有氧暴露环境下更容易发生二次发酵,因此,有必要在青贮中使用添加剂,以保证HSS在使用过程的营养品质。

In order to promote the exploitation and utilization of sweet sorghum silage,three kinds of silages（high sugar sweet sorghum silage,HSS; low sugar sweet silage,LSS; maize silage,MZS） were used to analyze the changes in dry matter（DM）,water soluble carbohydrates（WSC）,pH,temperature and microbial populations during aerobic exposure over 0,5,10,15,20 and 25 days.The results showed that HSS had a lower pH and higher LAB（lactic acid bacteria）population and higher temperature compared with LSS and MZS（P〈0.05） in the early stage of aerobic exposure（0-5 d）.The numbers of yeast,mould and aerobic bacteria in HSS were higher than that in LSS and MZS（P〈0.05）,while temperature and pH were lower in LSS than those in HSS and MZS（P〈0.05） in the latter stages of aerobic exposure（15-25 d）.HSS had the highest WSC and LSS had the lowest dry matter content（P〈0.05） over all exposure periods.Overall,LSS had the greatest aerobic stability with less yeast,mould and aerobic bacteria which were highest in HSS which had the lowest aerobic stability; bacteria numbers and aerobic stability were intermediate in in MZS.The results of this study suggest that it is necessary to use additives when making HSS to assure quality because it is more prone to secondary fermentation under aerobic exposure.