Toxicity And Mechanism Of Zearalenone On Laying Hens

This experiment was conducted to study the effects of zearalenone?ZEA?at different levels on serum biochemical parameters,antioxidant properties,organ index,reproductive hormone,organ histopathology and ZEA feces and urine residues in laying hens.Forty-four laying hens were randomly divided into four groups with 11 replicates in each group and 1 in each replicate.The control group was fed with the basic diet,while the experimental group I,II and III were fed with the experimental diet supplemented with ZEA at 1500,2500 and 3500 ug/kg,respectively.The preliminary period is 8 days and the ongoing period is 35 days.The trial period is divided into three stages:1¹4 days in the early stage,15²8 days in the middle stage and 29³5 days in the later stage.Serum samples were collected at different stages for the determination of reproductive hormone levels.On the last day of the experiment?35 days?,five laying hens were randomly selected from each group.After blood was collected from the cervical vein to separate serum,visceral tissues?liver,kidney,spleen?and reproductive organs?ovaries and fallopian tubes?were slaughtered routinely to determine serum biochemical indicators,antioxidant capacity,organ index,reproductive hormones,histopathological changes and toxin residues.The results are as follows:?1?Dietary addition of 1500³500 ug/kg ZEA could lead to abnormal liver metabolic enzyme activity in laying hens..Compared with control group,alkaline phosphatase?ALP?,alanine aminotransferase?ALT?and alanine aminotransferase?ALP?in each experimental group and glutamate transpeptidase?GGT?of group II and III increased significantly?P<0.01?,while GGT in group I remained unchanged;AST in group I,II and III increased gradually,with no significant difference?P>0.05?.?2?Adding 1500³500 ug/kg ZEA in diet could reduce the antioxidant capacity of laying hens.:Compared with the control group,the GSH-Px showed a downward trend,with no significant difference?P>0.05?.The T-AOC in serum test group III was significantly decreased?P<0.01?,The SOD of serum test II and III groups were significantly decreased?P<0.05?.The MDA in group III was increased?P<0.01?.TAOC in serum test group III was significantly decreased?P<0.01?.?3?Adding 1500³500 ug/kg ZEA in diet could affect organ index of laying hens.Compared with control group,ovarian organ index and kidney organ index of test III group and test II and III group were significantly increased?P<0.05?,but there was no significant effect on oviduct,liver and spleen organ index?P>0.05?.?4?ZEA?2500³500 ug/kg?could significantly reduce the progesterone?PROG?content in the middle stage?28 days?of experiment II and III?P<0.05?,but had no significant effect on estradiol?E₂?,luteinizing hormone?LH?,follicle stimulating hormone?FSH??P>0.05?.?5?ZEA can lead to histomorphological changes of fallopian tube,liver and kidney in different degrees:compared with the control group,hepatocyte swelling,steatosis,diffuse necrosis of liver,disorder of hepatocyte cord,hemorrhage and congestion of hepatic sinusoids,glomerular atrophy,lymphocyte infiltration,atrophy of renal tubular epithelial cells,steatosis and diffuse necrosis occurred in the later stage of the experiment?35d?.The basement membrane was exfoliated and the structure was incomplete in group II and III.The single columnar epithelial cells in the enlarged part of fallopian tube were enlarged,the uterine glands were reduced,the capillaries were congested and lymphocyte infiltrated.?6?With the increase of ZEA addition,the excretion of ZEA and its metabolite?-ZOL in feces showed an upward trend.ZEA can lead to abnormal activities of metabolic enzymes in the liver of laying hens and destroy their antioxidant capacity,affect the index of kidney organs?2500³500 ug/kg?and ovarian organs?3500 ug/kg?,affect the secretion of reproductive hormones?progesterone?,and destroy the morphology of reproductive organs?fallopian tube?.