An experiment was carried out to investigate the impact of high doses of dietary vitamin E on antioxidant status in broiler chickens (Ross 308) experimentally infected with Eimeria tenella. One day old chicks were assigned to five groups (25 each) and given basal diet (A and B) or basal diet supplemented with 100, 316 or 562 mg/kg of vitamin E (C to E), respectively. On the 21st day, all chicks except those in group A were inoculated with E. tenella and monitored for any change in blood vitamin E, malondialdehyde (MDA) and superoxide dismutase (SOD). Plasma vitamin E decreased by infection, but increased with dietary vitamin E (p<0.05). A significant rise of plasma and erythrocyte MDA was observed in infected birds (p<0.05), however, the chicks fed diet with 316 mg/kg added vitamin E had a lower MDA compared to infected controls (p<0.001). The erythrocyte SOD was not affected by infection (p>0.05), but it was significantly higher in group D than in groups B and E (p<0.05). In conclusion, addition of dietary vitamin E at 316 mg/kg can afford antioxidant protection to chickens infected with E. tenella, but at higher doses it may aggravate the unbalanced oxidant/antioxidant status.
Key words: Eimeria tenella, oxidative stress, broiler chickens, vitamin E, malondialdehyde, superoxide dismutase.
MDA, Malondialdehyde; SOD, superoxide dismutase.
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