Effect of dietary selenium and vitamin E on the ultrastructure and ATP concentration of boar spermatozoa, and the efficacy of added sodium selenite in extended semen on sperm motility

Three experiments evaluated the effects of dietary Se and vitamin E on the ultrastructure of spermatozoa, ATP concentration of spermatozoa, and the effects of adding sodium selenite to semen extenders on subsequent sperm motility. The experiment was a 2 x 2 arrangement of treatments in a randomized complete block design. A total of 10 mature boars were fed from weaning to 18 mo of age diets fortified with two levels of supplemental Se (0 or .5 ppm) or vitamin E (0 or 220 IU/kg diet). The nonfortified diets contained .06 ppm Se and 4.4 IU vitamin E/kg. In Exp. 1, the spermatozoa from all boars were examined by electron microscopy. Vitamin E had no effect on structural abnormalities in the spermatozoa. When the low-Se diet was fed the acrosome or nuclei of the spermatozoa was unaffected, but the mitochondria in the tail midpiece were more oval with wider gaps between organelles. The plasma membrane connection to the tail midpiece was not tightly bound as when boars were fed Se. Immature spermatozoa with cytoplasmic droplets were more numerous when boars were fed the low-Se diet, but the occurrence of midpiece abnormalities occurred in boars fed diets with or without Se or vitamin E. Our results suggest that Se may enhance spermatozoa maturation in the epididymis and may reduce the number of sperm with cytoplasmic droplets. In Exp. 2, the concentration of ATP in the spermatozoa was evaluated in the semen of all treatment boars. When the low-Se diet was fed, ATP concentration was lower (P < .01), whereas vitamin E had no effect on ATP concentration. Experiment 3 investigated the effect of diluting boar semen with a semen extender with sodium selenite added at 0, .3, .6, or .9 ppm Se. Three ejaculates from each boar were used to evaluate these effects on sperm motility to 48 h after dilution. Sperm motility declined (P < .01) when Se was added to the extender, and this decline was exacerbated as the concentration of added Se increased (P < .01). The added Se was demonstrated to be tightly adhered to the spermatozoa. Overall, these results suggest that low Se-diets fed to boars resulted in abnormal spermatozoal mitochondria, a lower ATP concentration in the spermatozoa, and a loose apposition of the plasma membrane to the helical coil of the tail midpiece, but no effect from inadequate vitamin E was demonstrated. Adding sodium selenite to the semen extender reduced sperm cell motility.