Selenium efficiency in protecting sperm quality and testicular parameters of South African indigenous Zulu rams exposed to heat stress

The study investigated selenium's (Se) efficiency in preserving South African Zulu rams' sperm quality and testicular parameters when they were exposed to heat stress. Indigenous Zulu rams (20) between 2 and 5 years old were allocated into four groups, namely the Se, testicular heat stress (THS), selenium plus testicular heat stress (SeTHS), and control. Each group comprised five rams; the groups were balanced according to the rams' body weight and scrotal circumference. The Se and SeTHS groups received sodium selenite orally bi-weekly for 5 months. To induce heat stress, testicular heat insulation bags were wrapped around the testes of the rams receiving the THS and SeTHS treatments for 49 days. Semen was collected from the rams weekly from the third month onward; the first two months were for Se & THS acclimatization. In addition, testicular measurements were taken bi-weekly. Analysis of variance was used to analyze the sperm quality data. Duncan's multiple range test was used to compare the groups' data for significant differences. The results showed that the Se-supplemented rams' scrotal circumference was smaller (p < 0.05) compared with the other groups. The Se, SeTHS, and control groups demonstrated similar total sperm motility; in contrast, the THS and SeTHS groups recorded low and high total sperm motility, respectively, compared with other treatment groups (p < 0.05). The semen from the rams that received THS without Se displayed a significantly higher number of immotile sperm cells (p < 0.05) and poor sperm quality, including total and progressive motility, and kinematic parameters when compared with other treatments, suggesting that Se protects sperm against THS. We concluded that selenium protected some sperm parameters (TSM, PSM, MV, VCL, VSL) of THS- treated rams while others did not improve (RV, NSM, C, STR).