模拟降雨和风干对玉米青贮营养品质及有氧暴露期微生物数量的影响

Effects of simulated rainfall and air drying on the quality of corn silage and microbe quantity after aerobic exposure

本试验旨在研究模拟降雨和风干对玉米青贮过程中营养品质的影响。选取蜡熟期去穗玉米秸秆粉碎后分为3组,模拟降雨组(RAIN)通过人工喷水完成,每2 h喷洒一次,每次每吨玉米秸秆喷洒2 L水,喷洒3次,风干组(DRY)自然风干6 h,对照组(CON)不作任何处理。将3组秸秆放入20 L的自制青贮发酵桶制作青贮饲料,每组制作30桶,共发酵50 d。测定玉米青贮的化学成分、发酵品质;青贮第50天模拟开窖,打开剩余的青贮桶,同时在发酵桶模拟开窖后第0、1、3、7、15天分别检测微生物数量。结果表明:对照组粗蛋白质(CP)、乳酸(LA)、乙酸(AA)含量分别较模拟降雨组高0.43%、2.39%、0.31%(P <0.05),分别较风干组高0.39%、0.95%、0.13(P <0.05),而中性洗涤纤维(NDF)、pH、氨态氮含量显著低于模拟降雨组和风干组(P <0.05),模拟降雨组水溶性碳水化合物(WSC)含量分别较对照组和风干组低2.81%、1.63%(P <0.05),对照组未检测到丙酸(PA)和丁酸(BA)的存在。有氧暴露第3天时,对照组霉菌含量较模拟降雨组低0.99(P <0.05),随着有氧暴露时间的延长,各处理组均呈现酵母菌、霉菌逐渐升高,乳酸菌逐渐降低的趋势。综上所述,降雨和风干都会使青贮营养品质降低,影响青贮饲料的保存与利用。

This study was conducted to observe the effects of simulated rainfall and air drying on the quality of corn silage.Corn straw without grain which was at dough stage was selected and divided into 3 groups after grinding.Artificial sprayed water was regarded as simulated rain group(RAIN),artificial sprayed water was once two hours,2 L/t water was sprayed each times,three times in total.Air drying for 1 d was regarded as air drying group(DRY).The control group(CON)was not treated at all.Whole corn straw in 3 groups was used to make silage and stored in 20 L self-made silos for 50 d and then determined chemical composition,fermentation quality,microbe quantity.The results showed that the content of crude protein(CP),lactic acid(LA),acetic acid(AA)in CON were increased by 0.43%,2.39%,0.31%(P<0.05)than RAIN,and were increased by 0.39%,0.95%,0.13(P<0.05)than DRY,neutral detergent fiber(NDF),pH,NH3-N were decreased significantly than RAIN and DRY.The content of water soluble carbohydrates(WSC)was decreased by 2.81%,1.63%(P<0.05)in RAIN than CON and DRY.In CON have no propanoic acid(PA),butyric acid(BA)were detected than RAIN and DRY(P<0.05),After aerobic exposure 3 d,the content of mold was increased by 0.99%(P<0.05)in CON than RAIN and DRY,with the extention of aerobic exposure time,all the groups showed a trend of the yeast and mold were increased,lactic acid bacteria was decreased gradually.In conclusion,rainfall and air drying will reduce the nutritional quality of silage and affect the preservation and utilization of silage.