**5. Effect of PE on hepatic antioxidant content**

Dietary PE supplementation significantly improved hepatic vitamin E (P < 0.001) by 33.4% and coenzyme Q10 (P < 0.05) by 28.6% (**Table 2**). No changes (P > 0.05) were observed in hepatic antioxidants content due to dietary type (P > 0.05), although the response of wheat based diets tended (P = 0.062) to be higher compared to maize based diets. More importantly, the increase in G:F and NE is coupled with the increase in the hepatic concentrations of vitamin E and coenzyme Q10 [48].

Infectious diseases have been demonstrated to reduce tissue antioxidants [52], suggesting that higher concentrations of vitamin E and coenzyme Q10 in liver may decrease the challenge provoked by infectious diseases. In addition, feeding a combination of PE in the current study resulted in not only improved feed efficiency, but also increased hepatic antioxidants retention compared with the non-supplemented diet. When birds are reared under commercial farm conditions, where the potential for challenge is greater, and fed diets supplemented with PE, then there may be improvements to their overall nutrition, antioxidant and health status, and resistance to diseases [48]. The improvements observed may indicate that vitamin E and coenzyme Q10 may be effective at reducing production and effects of free radicals [53]. Coenzyme Q10 is provided by the diet, however significant levels are also produced in the body. Increased concentration of coenzyme Q10 in the liver of the growing chickens is therefore likely the result of dietary PE supplementation and dietary sources should thus be considered beneficial at improving the antioxidant status. It has also been reported [13] that PE, increased the activity of the antioxidant enzymes of the mucosal cells of rats, thus reducing the intestinal cell damage and cell turnover and sustaining the integrity of the intestinal mucosal layer.
