Abstract

This study examined the effects of vitamin E on daily intake, serum testosterone levels, and epididymal sperm quality in heat stressed male rats.  Rats were heat stressed (HS; 35°C) or housed at room temperature (control; 24°C) for 20 days and offered one of the following dietary vitamin E concentrations: 42 (low), 242 (med-low), 2,042 (med-high), or 20,042 (high) IU/kg diet. On day 21, rats were euthanized.  In rats offered a low vitamin E diet, serum testosterone was greater (P = 0.002) in controls than in HS rats on the same diet. However, serum testosterone did not differ (P > 0.201) between controls and HS rats offered other dietary vitamin E levels.  Epididymal sperm motility was reduced (P = 0.002) in HS rats compared to controls independent of vitamin E level, while sperm cell concentration was reduced (P = 0.010) in HS rats offered med-high dietary vitamin E compared to controls of the same diet. Sperm cell morphology did not differ between HS and control rats (P = 0.183). No sperm trait mentioned above was affected by dietary vitamin E level (P > 0.170). Testicular weight (P = 0.005) was reduced in HS rats, but not affected (P > 0.190) by vitamin E.  Data indicate testicular mass loss and mild adverse effects on some components of male fertility due to heat stress However, these effects were inconsistent and were not relieved by increased dietary vitamin E concentration. Interestingly, no organ lesions were observed in rats consuming extreme amounts of vitamin E and vitamin E concentration did not influence intake or weight gain.

Key words: Epididymal sperm collection, heat stress, sperm quality, vitamin E.