The Accumulation And Control Technology Of Aflatoxin In Whole Crop Corn Silage

The whole crop corn silage is an important feed for dairy cattle in China.Aflatoxin in feed seriously affected quality and safety of dariy cattle.The composition and content of aflatoxin and its dynamic change through corn forage to whole crop corn silage just opened and to whole crop corn silage after aerobic exposure were studied in this research.The effects of nitrogen fertilization,fungal species and corn varieties on the aflatoxin of whole crop corn silage were analyzed and the effect of self-developed additives to control the aflatoxin content of whole crop corn silage was discussed.The main results are as follows:(1)Under natural conditions,aflatoxin was detected in the corn forage and whole crop corn silage just opened and after 7 days of aerobic exposure,and its content was affected by corn variety and nitrogen application.For all tested samples,the aflatoxin contents were lower than 20?g kg-1 DM,and there was an increasing trend of aflatoxin content during ensiling.In the Hengshui area,the aflatoxins detected in whole crop corn silage were mainly AFB1,AFB2 and AFG2 which were mainly AFB1 and AFB2 in the Zhuozhou area.The interaction of corn varieties and nitrogen fertilization could affect the total content of alfatoxins.To reduce the total content of aflatoxin in the whole crop corn silage,the Beinong 208 needed to apply 150 kg/hm~2 nitrogen fertilization rate in the field.While for the Xianyu 335 or the Jingke 516,it would be 450kg/hm~2 or 600kg/hm~2 nitrogen fertilization rate in the field.(2)Microbial diversity in corn silage was affected by nitrogen application rates and corn varieties under natural conditions.The relative abundance of Candida spp.was higher,while the relative abundance of the Hypocrea spp.and Weissella spp.were very lower when the nitrogen fertilization rate in the field was higher.For the whole crop corn silage made by Beinong 208,600 kg/hm~2 of pure nitrogen in the field had a relatively lower abundance of Lactobacillus spp.and Klebsiella spp.and higher abundance of Citrobacter spp.and Hannaella spp.While in the whole crop com silage made by Jingke516,it would be 300 kg/hm~2 of pure nitrogen.(3)Different toxic fungi had significant effects on the composition and content of aflatoxin in whole crop corn silage.After inoculation of fungi,the contents of aflatoxin decreased from corn forage to the just opened corn silage and to the corn silage after 7 days of aerobic exposure.AFB1 and AFB2 were detected by inoculation AF in the field,which would be AFB1,AFB2,AFG1 and AFG2 by inoculation AP in the field.The aflatoxin contents were significantly affected by fungal species and silage types.(4)Addition of AF during harvest decreased the AFB1 content of the whole crop corn silage and affected by the additives.PNa treatment led to the lowest AFB1 content of the whole crop com silage.The AF + LP treatment increased the content of aflatoxin of whole crop corn silage which increased to more than 20?g kg-1 DM after 14 days of aerobic exposure.LB treatment group increased the aerobic stability of the whole crop corn silage,but the aerobic stability of the AF + LB treatment group was worse.The increase of aflatoxin in whole crop corn silage during 7 days of aerobic exposure was less than that of LP treatment.(5)After inoculation of AF in the field,LAB had significant effect on aflatoxin content in whole crop corn silage.AF + LB can rapidly reduce the aflatoxin content during the first 7 days of ensiling.AF+ LB or AF + LB + LP increased the AA content after 90 days of ensiling,inhibited the number of molds,especially the number of Aspergillus flavus,increased the aerobic stability and decreased the aflatoxin content of whole crop corn silage.The relative abundance of Candida spp.,Paecilomyces spp.,Aspergillus spp.and Aspergillus flavus was lower,the aerobic stability was higher and the aflatoxin content was lower for the AF + LB treatment than AF treatment in the whole crop corn silage just opened and after 7 days of aerobic exposure.With the increase of pH value,the relative abundance of Candida spp.and Penicillium spp.increased rapidly,but AF + LB significantly decreased the relative abundance of Penicillium spp.