**5.4 Role of selenium in reproduction**

Studies have reported the association of selenium in animal and human reproduction. Selenium plays unique roles in fertility, placenta retention, synthesis of sperm and testosterone. Consumption of selenium deficient diet has been linked to poor growth and reduced fertility [51]. Changes in the luteinizing hormone receptors of Leydig cells observed selenium deficiency as it affects secretion of testosterone (Thomson and Robinson; [52]). Several studies have reported the protective effect of selenium in cadmium-induced toxicity. Selenium plays a role in inhibiting the growth of cancer cells in prostate cancer subjects by inhibiting RNA, DNA and protein synthesis [53]. Selenium has been reported to impact the entire morphology of the testis [54]. Selenium has been shown to increase fertility in dairy sheep [55]. Pastures with very low selenium levels were found to have increased fertility when administered selenium supplements [40]. Such an increase was not observed when the supplement was replaced with vitamin E. Administering selenium supplements to pregnant Ewes increased the rate of lamb's survival during the first 10 days [37]. Injection of selenium decreased the formation of ovarian cyst in cows with deficient diet [56]. Prolapse of the cervix was attributed to selenium deficiency, while red blood cells with low selenium concentrations were reported in women undergoing uncontrolled abortions [57]. Fertility and sperm was improved after consumption of selenium in a study conducted in Scotland [57].
