Effects Of Alfatoxin B₁on Concentration Of Milk Aflatoxin M₁Production Performance And Blood Biochemical Indicators In Holstein Cows

Aflatoxin is derived from mycetes, and has proved to be a carcinogen for human.AFM₁is the metabolite of AFB₁. When cows are fed with AFB₁-tainted feed, AFM₁will bedetected in the milk. Every country controls the content of AFM₁in milk strictly. So it is ahot topic that how to prevent and treat with the contamination of AFB₁.This experiment was conducted to study the effect of AFB₁on the performance and theblood biochemical parameters of the cattle, and it also evaluated the content of AFB₁andnutrition change in corn silage when the second fermentation of corn silage was performedin different temperature. The purpose of the study is to improve the feed safety of the cattle,control the content of AFB₁in feed lower than the threshold value, and provide a theoreticalbasis for the control of content of AFM₁in fresh milk and milk products.Test one The effect of AFB₁on the fermentation in vitro and the degradation rate offeed.The rumen fluid was derived from three lactating Holstein cows with permanent rumenfistula. It was designed as randomized experiment of single factor with three treatments,consisting of three replicates. The profile of changes of related index of the cultrue hadmade by adding different concentrations of AFB₁（0.1,1.0,10μg/ml）. The results showed thatwith the increasing of the AFB₁, the content of propionic acid decreased gradually （p<0.05）,while the change of acetic acid, butyric acid and total VFA was not significant. Andcompared with the control group, the degradation rate of dry matter was decreased by5.89%in the treatment group with10μg/ml AFB₁, while the degradation rate of crudeprotein and neutral detergent fiber was not significant （P>0.05）.Test two The effect of AFB₁on the content of AFM₁in milk, the performance and theblood index.A3x3Latin square design was used to study the problem. Three mid-lactationHolstein dairy cows with permanent rumen fistula were selected. There were three levels offeed containing0μg/kg aflatoxin B₁,20μg/kg aflatoxin B₁,40μg/kg aflatoxin B₁respectively. The result showed that with the increasing of the AFB₁, the content of AFM₁inmilk increased significantly （P <0.05）, the concentration of lactose increased （P <0.05）, the changes of milk yield, the content of protein and fat in milk, the amount of dry matter intake,and the apparent digestibility of dry matter and crude protein were not significant. Theactivity of transglutaminase, aspartate transaminase, alanine aminotransferase, alkalinephosphatase, and lactate dehydrogenase, and the amount of IgG did not change significantly.The conversion efficiency of nitrogen during lactation decreased with the addition of. Theconversion efficiency of AFM₁were1.69%and1.28%when the addition amount of AFB₁were20μg/kg and40μg/kg.Test three The effect of temperature on the quality of whole corn after the secondfermentation.In order to simulate the environment of second fermentation, plastic bags and ovenwere used to study the content of AFB₁and the quality of whole corn silage when the wholecorn silage undergone second fermentation in different environment temperature （20、28、35℃）. The results showed that, with the increasing of temperature, the amount of lactic aciddecreased gradually, the pH value increased gradually （P <0.05）, and the content of crudeprotein decreased gradually （P <0.05）. When the temperature was35℃, the content ofAFB₁was highest, and the difference was significant （P <0.05）. The changes of aciddetergent fiber, neutral detergent fiber, acid detergent lignin, volatile fatty acid, acetic acid,propionic acid, and butyric acid were not significant.The results showed that, AFB₁could influence the ruminal fermentation of cows byreducing the degradation rate of dry matter and the content of VFA and propionic acid.The conversion efficiency of AFM₁into milk were1.69%and1.28%when the additionamount of AFB₁were20μg/kg and40μg/kg. So controlling the amount of AFB₁in feedlower than40μg/kg can prevent the amount of AFM in fresh milk and products fromexceeding the standard.