Effect of dietary vitamin E on plasma oxidative stress in broiler chicks infected with Eimeria tenella

The aim of the present experiment was to study the alterations in plasma oxidative stress parameters in broiler chicks fed with graded dietary vitamin E whilst infected with Eimeria tenella. Ninety six new-born chicks were assigned into three treatment groups by adding 0, 316 or 562 ppm of vitamin E premix to their regular diet. On day 21, half of the experimental birds were inoculated with 4 × 10⁴ sporulated oocysts of E. tenella per bird; whereas the remaining chicks served as non-infected controls. Blood samples were taken and assayed for total antioxidant activity (TAA), lipid peroxidation level and vitamin E content. Oocyst shedding was also examined in all treatments. Results showed that TAA and vitamin E levels in plasma were not affected by dietary treatment (p > 0.05). The lowest level of plasma lipid peroxidation (p < 0.001) was noticed in the chicks treated with 562 ppm of dietary vitamin E, but the difference between the chicks fed a regular diet or 316 ppm dietary vitamin E was not significant (p > 0.05). The oocyst shedding was the lowest in the chicks treated with 316 ppm dietary vitamin E (p < 0.001), but there was no significant difference between the other two dietary treatments (p > 0.05). In conclusion, the addition of vitamin E at a rate of 316 ppm to broiler basal diet can improve cellular defence system against E. tenella infection without any effect on the plasma antioxidant status, but at higher values it may have an adverse effect.