Pathological Study On The Carp Fed Oxidized Fish Oil And The Protective Effect Of Vitamin E

Experimental fish diets contained 10% fish oil which had been oxidized to four degrees (peroxide values of 3.6,69.5,145.3 and 263.6 mEqO2/kg oil). There were three levels of Vitamin E (50,100,and 150 lU/kg diet) supplementation. The harm of the oxidized fish oil rose when its peroxide values increased. The conditions induced by oxidized oil were improved by the addition of vitamin E. The morbidities in the carp fed diets (Vitamin E of 50 lU/kg diet) were76.7%,40.0%,16.7%,0%,while the mortalities were 40.0%,23.3%,10.0%,0% ,respectively,for peroxide values of 263.6,145.3,69.5,and 3.6 mEqO2/kg oil. When the supplementation of Vitamin E is 100 lU/kg diets ,the morbidities were 23.3%,13.3%,0% and 0%,The mortality in the first group was 16.7%,while there was no death occurred in the other groups. The morbidities in the carp fed diets (Vitamin E of 150 lU/kg diets) were 6.7%,0%,0%,0%,while there was no death occurred in these groups. The fish fed diets containing oxidized fish oil exhibited poor growth,increase of mortality,reduction of lateral muscle and high incidence of exudates (generalized edema,exophthalmia,scale erection). Necropsy showed muscle atrophy,tumefaction in both the liver and kidney. Focal necrosis was occurred in the liver with the color being bluish. Red muscle fiber in the lateral body was discolored and its texture turned to be obscure. Histologically,great changes were appeared in the muscle fibers,liver and pancreatic tissue. Liver tissue showed vacuolation and coagulation or lytic focal necrosis;while pancreas tissue appeared acinus atrophy,degeneration,and necrosis. The blood capillary of kidney tissue took on dilatation,hyperemia and hemorrhage. The atrophy,degeneration and necrosis in the muscle fibers were significantly. The musclefibers were arranged disorderly. The interspaces of the fibers were enlarged significantly. Ultrastructurely,the mitochondria of cardiac muscle fiber and hepatocyte showed swelling,expanding,and disorganization. Cardiac muscle membrane were swellen and expanded. Its intermembranous space was enlarged. The intercalated disk was indistinct or extinct. Hepatocyte nucleus were fragmentized. The chromatin of hepatocyte was electron-lucent. The microvilli were sheded off from renal tubular epithelial cell. The lysosome in renal tubular epithelial cell was increased. Haematologically,the number of RBC,hemoglobin,and Vitamin E concentration in plasma decreased,while the MDA concentration in plasma increased. Plasma superoxide dismutase (SOD) and glutathione peroxidase (GSH-P) activities descended,while the SOD and GSH-PX activities of the fish fed diets containing 69.5 mEqOlkg oil were not affected by the oxidized fish oil during the fist 8 weeks.