Effects of organic and inorganic selenium supplementation on frozen-thawed ram semen at two cooling periods.

Abstract

The aim of this study was to evaluate the effects of different selenium compounds on the sperm quality of cryopreserved ram semen. Ejaculates from four rams, collected using an artificial vagina heated to 38°C, were individually evaluated. The approved ejaculates were pooled and diluted (1:1 v:v) in Tris-egg yolk extender (20%, v/v) and separated into two control groups, one cooled for 2h and the other for 4h. The pooled ejaculates at the two cooling periods were supplemented with two doses (0.5 and 1μg/mL) of organic selenium (ORG), and inorganic selenium (SeNa), each. The samples were packed in 0.25ml straws, at a concentration of 400 × 106 sperms/mL and stored in liquid nitrogen. The straws were thawed in a water bath at 37°C for 20s, and the samples were subjected to sperm kinetics evaluation by Computer Assisted Semen Analysis software. Sperm membrane integrity, acrosome morphology, and mitochondrial potential were assessed. In addition, oxidative stress markers reactive oxygen species (ROS), ferric reducing antioxidant power (FRAP), thiobarbituric acid reactive species (TBARS), and glutathione peroxidase (GPx) enzyme activity) were also evaluated. No significant improvement was observed in the ram semen quality at the two cooling times. Supplementation of the freezing extender with 0.5μg/mL ORG, subjected to 4h cooling period, increased the sperm motility when compared with the control group at the same cooling time. In addition, the 0.5μg/mL SeNa group, under the 2h cooling period, showed an increase in sperm motility when compared to the control group at the same cooling period. Considering the importance of sperm motility as a fertility parameter, our study indicates that supplementation with ORG and SeNa can help improve the total motility of the cryopreserved ram semen.