| Abstract: |
Vitamins D3 and A are very important nutritive feed additives in chickens and both have a great role in theirgrowth promotion.The present work was performed to study the effects of hypervitaminosis D 3 or A on some serum biochemical parameters of broiler chickens , beside the associated histopathological changes. Also to investigate thepossibility of an antagonism between excesses of the two vitamins in chickensOne hundred and forty four male broiler chicks ( from oneday old) were used in this study. They were divided into two main equal groups (gp. I 4 weeks and gp. 11 6 weeks) according to the duration of vitamins addition which began at one dayold. Each of the main groups was subdivided into nine subgroups ( according to the added levels of vitamins to the ration): subgroup. 1 - control ( normal requirement 500 IU Vit. D3 + 2,600 IU Vit. AI kg diet) , subgp. 2 - (5,000 IU Vit. D3 / kgdiet) , subgp.3-(50,000 IU Vit. D3 / kg diet) , subgp. 4- (500,000 IU Vit. D3 /kg diet) , subgp. 5 - (26,000 IU Vit. A / kg diet), subgp. 6- (260,000 IU Vit. A / kg diet), subgp. 7-(2,600,000IU Vit. A / kg diet) , subgp. 8- (50,000 IU Vit. D3 + 260,000 IUA /kg diet) , and subgp. 9 (500,000 IU Vit. D3 + 2,600,000 IU Vit. A / kg diet). Chickens in all subgroups were weighed .
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