Effect of dietary vitamin E on CoQ10 levels in phesant semen

CoQ10 is measured in different animal tissues. It is a potent antioxidant and a free radical scavenger in various biological systems; moreover it supports alpha-tocopherol effect by regenerating the vitamin from its oxidized form. In human, semen CoQ10 evaluation showed correlation with sperm count and motility and gave useful information about fertilizing ability in man. The observation that alpha-tocopherol and CoQ10 mutually interact enhancing membrane resistance against oxidative damage induced ourselves to investigate CoQ10 levels of seminal plasma of pheasant fed high dietary levels of vitamin E. Twenty-six pheasants, good semen donors, chosen from open air individually caged males, were randomly assigned to two dietary groups (13 males/group) at 33 weeks old: Control group fed a commercial diet for breeders, containing 40 mg alpha-tocopherol Kg-1 feed; Vit E-100 group fed the same commercial diet supplemented with 100 mg alpha-tocopherol Kg-1 feed. Semen was assayed for the quantitative determination of CoQ10 by RP-HPLC-Fl method at 37 weeks of age (corresponding to April the 4th) and from May the 20th to July the 15th, at 7-day intervals. Data were processed by analyses of variance considering male, dietary group and period of year as source of variation. The April total CoQ10 determination was considered as the starting value and the followings were grouped on two periods that differed in environmental mean maximum temperature: lower 25°C (May-June period) or higher 25°C (June-July period). Throughout the reproductive season, pheasant semen CoQ10 level indicates an overall increasing trend in both groups. The increasing environmental maximum temperature could cause animal stress leading to cellular oxidative damage, consequently a more effective endogenous antioxidant mechanism could be required. At the end of the experimental period, CoQ10 values of vitE-100 group were significantly higher than those at the first determination. The overall increasing trend of CoQ10, since it is an antioxidant molecule involved in the defence of the cell from free radical damage, may represent a mechanism of CoQ involvement in ejaculate vitamin E metabolism. To better understand the antioxidant activity of the supplemented vitamin E and the CoQ10 biochemical interactions, CoQ10H2/CoQ10 rate should be envisaged.