Seminal plasma hormonal profile of Arabian stallions that are classified ‘good’ or ‘poor’ for semen freezing

Abstract

ObjectiveTo relate seminal plasma reproductive and metabolic hormone profile to both semen freezability and post-thaw semen characteristics. MethodsSemen was collected from each Arabian stallion (N = 16) for five consecutive weeks and evaluated before conducting this study. Seminal plasma was collected during semen processing for measuring leptin, insulin, Insulin like growth factor-I (IGF-1), cortisol, testosterone, estradiol and thyroid hormones. Stallions were classified into good (N = 10) and poor freezer (N = 6). Semen post-thaw motility (%), viability index, membrane and acrosome integrity (%) were also evaluated. ResultsGood freezer stallions had significantly (P = 0.0001) high cortisol, estradiol, insulin, IGF-1, T3 and T4, but significantly low leptin (P = 0.003). Post-thaw sperm viability index (P = 0.0001), membrane integrity (%) (P = 0.002) and motility (%) (P = 0.0001) at 0, 1, 2 and 3 h of good freezer stallions was significantly high compared to poor freezers. Testosterone, insulin and IGF-1 in seminal plasma of good freezer stallions had significant (P < 0.01) positive correlation with sperm post-thaw viability index but estradiol and insulin in seminal plasma of poor freezers correlated with sperm post-thaw viability index. Within good freezer stallions, testosterone in seminal plasma correlated positively with both viability and acrosome integrity but within poor freezer stallions it had a negative correlation with both of them. Individual variation existed between animals and significantly affected seminal plasma hormones and semen post-thaw characteristics. ConclusionGood freezer stallions could be selected depending on assaying seminal plasma hormones. Both estradiol and IGF-1 could be used as semen extender supplementation to improve sperm post-thaw motility, viability and acrosome integrity.