Study On The Main Mycotoxins Transfer Into Milk And Its Effects On Productive Performance And Health In Dairy Cows Fed Diets Naturally Mildewed

In this study,using naturally mildewed feedstuffs as the research objects,the main mycotoxin risk of dairy cattle sorting,screening,optimization and production of natural moldy feed raw materials,natural moldy cottonseed and moldy corn surface as the source,design 5 groups of different proportion of moldy feed raw materials containing different concentrations of mycotoxin test diets(Control,50 Cot,100Cot,50 CotCorn and 100CotCorn),to study the influence of natural moldy feed on feed intake of lactating dairy cows,milk performance,milk composition,rumen fermentation,body health and the main mycotoxin AFB1,ZEA,DON conversion,ane the regulation in the milk residue and elimination.The main contents are as follows:(1)Risk prioritizing of the mycotoxins residues in dairy cow feedstuffs.Through sampling found that six feed ingredients(silage maize,corn flour,wheat bran,cottonseed,shotcrete corn bran,flaked corn)have big risk with the high bottom level of the mould and mycotoxin pollution,should focus on monitoring and management.Compared to China,Europe,the United States and other organizations for dairy cattle feed mycotoxin residues,reference mycotoxin detection reports,combined with the results on domestic typical scale dairy field commonly used 12 kinds of feed raw material,to determine AFs as I risk management of mycotoxin,ZEA as II,DON III,both OTA and FUM as IV risk management of mycotoxins.T-2 toxin and HT-2 toxin,keep the general attention,not included in the ranking of risk management.Other categories of fungal toxins need to keep more attention to the observation directory.(2)Selection and preparation of naturally mildewed feedstaffs for dairy cow.Choose corn silage,corn flour,wheat bran and cottonseed,shotcrete corn bran and flaked corn,under natural conditions to add high and low water to mildew,and it found that cotton and corn mildew could respectively generate higher content of AFs,ZEA and DON.Then cottonseed and corn flour as raw materials of target mildew,respectively,with the addition of 7 moisture gradients(10%-70%)and 3 moisture gradients(10%-30%)to optimum mildew conditions.The results showed that under natural conditions the corn flour occurred mildew and toxins produced the optimum adding water proportion was 30-40%,optimal proportion 40%;cottonseed occurred mildew and toxin produced suitable adding ratio of water for 20-30%,the optimal ratio of 30%.Under the condition of natural moldy corn and cottonseed mildew toxin in different kinds and content,the moldy cottonseed was generated and enrichment of AFs,moldy corn mainly produce bioaccumulation of DON and ZEA.(3)The influence of natural moldy feed on growth performance,body health and function of dairy cow rumen microbial fermentation.Using natural moldy corn and cottonseed preparation different diets to feed dairy cows,dairy cows' daily feed intake,feed conversion and milk performance have adverse effects.The feed intake,milk yield and feed conversion rate of 50 CorCorn group and 100 CorCorn group were significantly lower than those of control group(P < 0.05),the yield of milk and feed conversion rate were 9.15% and 4.95% respectively.Through the influence of milk fat,milk protein,lactose,and other major constituents of milk synthesis,natural moldy feed raw materials can significantly reduce the total output of the milk fat,milk protein,lactose and milk solid compounds(P < 0.05),then caused loss of milk fat(the top loss 12.24%)and milk protein(the top loss of 15.25%).Cow serum AST,ALT,ALP and other indexes increased,TBIL,DBIL,I-BiL,such as content was increased significantly(P < 0.05),increasing the cow liver damage;Acetic acid,propionic acid and butyric acid concentration in the rumen fiquid decreased,and inhibit the normal fermentation of rumen.Mildew cottonseed,mildew cottonseed and mildewing maize combination between the different treatment groups,can produce additive effects of mycotoxin hazards.(4)The influence of natural moldy feed on rumen main functional bacterial growth of dairy cows.By using real-time quantitative PCR(q-PCR)method,to detece the 13 kinds of different treatment groups of moldy feed in rumen cellulolytic,fat,protein,starch,lactose utilization of functional microbes,including general prevotell,ruminococcus albus,ruminococcus flavefaciens,ruminococcus Bacteroides,ruminobacter amylophilus,fibrobacter succinogene,streptococcus bovis,eubacterium ruminantium,megasphaera elsdenii,prevotella brevis,anaerovibrio lipolytica,selenomonas ruminantium and prevotella bryanti ect.The functional microbes were relatively quantitative,and the results showed that 13 kinds of bacteria decreased to different extent,both the streptococcus bovis and megasphaera elsdenii was significantly decreased(P < 0.05),indicating that natural moldy feed on main rumen bacteria have inhibitory effect.With the diet of two kinds of moldy raw materials adding proportion increases,the number of the main function of rumen bacteria decreased.(5)The residue conversion,elimination in milk and the main mycotoxins transfer into milk with the natural moldy feed conditions.Under the condition of this experiment,cows fed contaminated feed ingredients(mildew cottonseed and moldy corn)formulated diets,AFM1,AFB1,ZEA,DON and other major mycotoxins can be transformed or residues in milk.The experiment of different diets in milk,AFM1 content for 0.007-1.583 ppb with transformed rate 0-2.87%;AFB1 content is 0-0.028 ppb with residual rate 0-0.049%;level of ZEA 0.034-0.082 ppb with residual rate 0.014%-0.050%;the content of DON 0.190-0.293 ppb with residual rate 0.012%-0.017%.In this study,the metabolites of ZEA were not detected in milk.Comparison of AFM1,AFB1,ZEA,DON conversion and residues in milk,the higher of the content of mycotoxins increase in the diet,the higher of the conversion and residual rate in milk.To the process of eliminating the mycotoxins in milk,the eliminated time and the speed of the different group were relevant to the content mycotoxins.After stopped feeding natural moldy feed diets and mycotoxins in milk eliminate AFM1 takes 5 to 7 days,AFB1 need 3-5 days,DON need 3 days,ZEA need 5 days.Because of the effect of the background of mytocoxins in dairy cows' diets,especially the DON and ZEA,the background value are obvious,which needs to be paid more attention.