The Contamination Of AFB₁in Feedstuffs And Effects Of AFB₁on The Liver Lipid Metabolism And Antioxidant Function In Laying Hens

The experiments were conducted to study the contamination of AFB1in feed raw materials, thecontamination of mycotoxins in corns, and effects of AFB1on the liver lipid metabolism and antioxidantfunction of laying hens.We collected84feeds from several provinces and cities, and then detected the content of AFB1by ELISA.The relevance ratio of AFB1was96.4%, but the exceeding standard rate was0. The ratio in feeds whoseAFB1content was less than20μg/kg was97.62%. We can presume that AFB1contamination in feeds wasnearly universal, but it seemed not a primal problem. We suggest take AFB1allowed limits in feed rawmaterials changed to20μg/kg, which is50or30μg/kg in Chinese standard.We collected36corns from several typical feed enterprises, and then detected the content of AFB1,ZEN,DON, OTA and FB1by ELISA. The relevance ratio of DON, ZEN, AFB1, FB1and OTA was100%,97.14%,91.67,88.89%and0respectively. The exceeding standard rate of DON, FB1and ZEN was33.33%,30.56%and14.29%respectively, these mycotoxins pollution was really serious. On the contrary, FB1and OTA was not outof limits. The related coefficient between ZEN and DON, between AFB1and FB1was0.512,0.489respectively,and they were both significant.Hepatocytes were isolated from livers of3days chick. Cells were incubated in williams’ medium Econtaining10%serum. After48h10%serum incubation and4h serum-free incubation, there were twotreatments, the control group contained no AFB1and the AFB1treatment group contained0.05μg/mL AFB1.The results found that aflatoxin B1treatment significantly increased the activity of GPT, GOT, and LDH andsignificantly down-regulated the expression of mRNAs for FAS, ACC, ME, LAR, apoB, MTP, CAT, Mn-SOD,Cu-Zn-SOD, and GSH-Px, and significantly increased MDA values compared with control, whereas there wasno significant influence on the expression of SREBP-1c mRNA, and the values of8-OHdG, and PCO. Therewas also no significant influence on the expression of GPR78and GPR94mRNA and GPR78proteinexpression. We can presume that AFB1can lead hepatocytes to a certain degree of damage. LXRs, notSREBP-1c was involved in the weakened expression of hepatic lipogenic genes by aflatoxin B1. Aflatoxin B1can reduce the antioxidant function of hepatocyt and cause lipid peroxidation. Hepatocytes were isolated from livers of3days chick. Cells were incubated in williams’ medium Econtaining10%serum. After48h10%serum incubation and4h serum-free incubation, there were fourtreatments, one of which had the same composition supplemented with AFB1(0.05μg/mL), ZEN(10μg/mL), orboth. The control group contained neither of the toxins. We can presume that AFB1and ZEN has certainantagonistic effect on the expression of mRNAs for FAS, ACC, LAR, Mn-SOD and Cu-Zn-SOD, and also hascertain additive effects on the expression of mRNAs for GPH-Px.Hy-line brown laying hens (69wk old, n=8) were injected with AFB1(55μg/kg weight) or DMSO (samedosage) for1wk. The results found that AFB1significantly decreased average egg rate, content of TG in serumand the expression of mRNAs for CPT. There was no significant influence on the body weight gain, averagefeed intake, liver development index, the activity of liver T-SOD, CAT and GSH-PX, and the values of MDA,8-OHdG, and PCO, and the expression of mRNAs for FAS, ACC, ME, LAR, apoB, MTP, andVLDL-Ⅱcompared with control. We can presume that AFB1has no effect on hepatic de novo lipogenesis, andthrough reduce lipid transportation, increase fatty acid oxidation and oxidative damage to decrease the contentof TG in serum.