Effect Of High Level Tin On Bursa Of Fabricius In Broiler

Heavy metal tin has been widely used in human production and life,most of the tin compounds remain in crops and pastures when used as insecticides,So the content of heavy metal tin in plant raw material is increased.In present studies,there are few reports on the effects of high tin on livestock and poultry.Therefore,in this study,we added different levels of tin in the diet to explore its toxic effects on the broiler bursa.200 healthy chickens were randomly divided into 4 groups of 50 chickens each.The control group was fed with basal diet.In the experimental group,400 mg /kg,800 mg /kg and 1200 mg /kg stannous chloride(SnCl2)were added to the basal diet,respectively.The trial continued for 42 days.At the 7th,14 th,21st,28 th,35th and 42 th day of the trial perio,we collected blood by jugular venous bleeding,recorded weight,and observed the clinical symptoms.The results showed that the weight of the bursa of the broiler was reduced compared with the control group.Histopathological observation revealed that the leptospirosis of the bursa was enlarged and the medulla lymphocytes were decreased.Detection the activities of superoxide dismutase(SOD),reduced catalase(CAT),glutathione(GSH)and malondialdehyde(MDA)of broiler bursa were measured via colorimetry,the results showed the activities of SOD,GSH and CAT in the bursin decreased and ROS levels and MDA contents increased.ELASA was used to detect the levels of IgA,IgG and IgM in broiler bursa,the results showed bursin immunoglobulin(IgG,IgM)contents were significantly reduced.The decrease of lymphocyte and immunoglobulin secretion was the direct cause of the damage of immune function of bursin.The changes of apoptosis rates and cell cycle were measured by flow cytometry.The apoptotic rate of lymphocytes in bursin was increased.The percentage of lymphocytes in G0/G1 phase and high tin group was significantly increased,and the percentage of bursal lymphocytes is reduced in S phase.