Role of seminal plasma in heat stress infertility of broiler breeder males

The present research was undertaken to determine the role of seminal plasma in heat stress (HS) infertility. Males were exposed to HS at 32 C or maintained at 21 C as controls. Centrifugation and reconstituton of semen samples created four final treatments: control sperm + control plasma (CsCp), control sperm + HS plasma (CsHp), HS sperm + HS plasma (HsHp), and HS sperm + control plasma (HsCp). Semen samples with HS males' seminal plasma had lower sperm quality index values than those containing plasma from control males. Seminal plasma from HS males diminished fertility of control sperm, and control seminal plasma did not improve fertility of HS sperm, Therefore, regardless of seminal plasma source, HS sperm had a lower fertilization rate than control sperm. Also, seminal plasma from semen samples with HS sperm (HsHp and HsCp) contained lower Ca, Na+, and Cl- concentrations than seminal plasma from semen samples with control sperm (CsCp and CsHp). When HS seminal plasma was mixed with control sperm, plasma ion concentrations increased, indicating an efflux of ions from the control sperm to the HS seminal plasma. On the other hand, when control seminal plasma was mixed with HS sperm, plasma ion concentrations decreased, indicating in influx of ions from the control seminal plasma to the HS sperm. Therefore, control sperm appear to have higher intracellular ion concentrations than the sperm from HS males. In conclusion, high temperatures might decrease male fertility by decreasing seminal plasma and intracellular ion concentrations.