Abstract

 
This study was conducted to determine the pathological sublethal toxic effects of selenium (sodium selenate) on broiler chickens. The 24h median lethal dose (LD50) of selenium was  0.72 mg/kg. Two sublethal doses were taken (0.02, 0.04 mg/kg) which constituted (3% and 6%) of the LD50. One hundred fifty one day old Rose broiler chicken were randomly divided into 3 equal groups, the first group was considered as control group (without treatment). The 2nd and 3rd groups were treated with natural requirement of selenium (0.3) mg /kg of diet. The 2nd and 3rd groups were treated with 0.02, 0.04 mg selenium/ kg (3% and 6%) respectively, orally. Eight chickens from each group were killed at 14, 24, 34 and 44 days of treatment and pathological lesions were recorded. The most important gross pathological changes in liver and kidney were paleness and petechial hemorrhage, congestion of the brain and heart blood vessels have been observed after 7 days of treatment in the 3rd group was more severe than that in 2nd group. The histopathological changes in liver were vacular degeneration of hepatic cells, hemorrhage and central veins congestion. Degeneration; coagulative necrosis of the tubular epithelial cells and interstitial hemorrhage in the kidney. The histopathological lesions were acute cellular degeneration; vacculation, hemorrhage and congestion of the brain blood vessels. In the heart there was hemorrhage with congestion and thickening of the walls of blood vessels. All changes were more severe in the 3rd group when compared with 2nd group.