Studies On Pathogenesis Of Experimental Copper Intoxication In Ducklings

210 one-day-old Tianfu meat ducklings were divided into three groups, and fed on diets as follow:l. controls (Cu 12.16 mg/kg), 2. copper toxic I (Cu 850 mg/kg) and 3. copper toxic II ( Cu 1050 mg/kg) for studies on pathogenesis of copper toxicity on organs, blood findings and immune function in duckling with the methods of experimental pathology and Flow Cytometry (FCM). The signs began to appear at the 2nd week in copper toxic group II and at the 3rd week in copper toxic group I. Some of affected ducklings died during the experiment. Pathomorphologically, there were similar lesions in copper toxic groups I and II when compared with control group. At necropsy, the cuticle of gizzard was thickened. The digestive tract was full of the black-brown, red-brown or light-green substance and intestinal mucosa was swelled. Lymphoid organs became smaller in both copper toxic group I and copper toxic group II than in control group. Histopathologically, the hepatocytes, renal tubules and cardiac muscle mainly showed granular and vacuolar degeneration. The epithelial cells of intestinal mucosa were degenerated and necrotic. The intestinal villuses were broken. Lymphocytes of lymphoid organs were depleted, degenerated and necrotic. Ultrastructurally, the mitochondria of hepatocytes were swelled, and its crista were broken or / and disappeared. The deposited substance with high electron density appeared in the cytoplasma and nucleus of hepatocyte, Changes of the mitochondria of lymphocytes of lymphoid organs were similar to these of hepalocytes. The apoptotic lymphocytes showed that the chromatin condensed and marginated, and the nuclei were crescent, "C-shaped, petal-like, or dark round. Also, apoptotic bodies were observed. Hematopathdogically, red cells in toxic groups I and II became deformed, degenerated and were enlarged or shrinked, or / and necrotic. The populations of red cells, hemoglobin contents and serum caeruloplasmin activity were much lower, and the serum copper concentrations, activities of glutamic pyruvic transaminase and glutamic oxaloacetic transaminase much higher in copper toxic groups than in control group.Immunopathologically, the weight and growth index of lymphoid organs were significantly reduced in copper toxic groups when compared with control group. The G0/G1 phase of cell cycle of bursa of Fabricius, thymus and spleen was much higher, and S, G2+M phases lower in copper toxic groups than in control group. Compared with the control group, the ANAE" positive ratio of peripheral blood lymphocytes and erythrocyte C3bRR and ICR ratio markedly decreased. The aforementioned results demonstrated that ducklings were susceptible to copper toxicity from 3 weeks of age to 5 weeks of age. The target organs of copper toxic injury were liver, kidney, heart, gastrointestines and lymphoid organs. The proliferations of lymphocytes were impaired, and T-lymphocytes were decreased in peripheral blood. The humoral, cellular and erythrocyte immune functions were reduced. The affected birds died due to the injury, disfunction of organs and reduced immune function.