Effect of Glutathione Supplementation to Semen Extender on Post-thawed Rooster Sperm Quality Indices Frozen After Different Equilibration Times.

BACKGROUND Avian sperm is susceptible to lipid peroxidation, compromising their fertility. The semen antioxidant system protects sperm plasma membrane against reactive oxygen species. OBJECTIVE The study evaluates the effect of glutathione (GSH) addition to semen extender during different equilibration times (ET) on rooster sperm cryopreservation. MATERIALS AND METHODS Semen samples are weekly collected from 60-week-old broiler breeder roosters. Collected samples were pooled and divided to six equal parts and frozen according to a randomized design (2 × 3 factorial arrangement). Treatments included adding two levels of GSH [0 (GSH-0) or 1 (GSH-1) mM] to semen extender during three ET: 0 (ET-0), 4 (ET-4) or 8 (ET-8) hours. Post-thawed motility and velocity parameters, apoptotic like changes, plasma membrane functionality, and mitochondrial membrane potential (MMP) were evaluated. RESULTS Post-thawed total motility is improved in the GSH-1 compared to the GSH-0 group (P<0.10). Total motility responded quadratically to increasing levels of ET such that the highest value is recorded at ET-0. Although progressive motility (PM) is not affected by GSH or ET, the highest PM is obtained in the GSH-1×ET-0 group (P<0.05). The VAP and STR is improved in the GSH-1 compared to GSH-0 group; however, VAP decreases quadratically, and STR decreases linearly as ET is advanced (P<0.05). The interactive effect of GSH by ET tends (P<0.08) to affect the wobble coefficient (WOB), such that the highest value is recorded in the GSH-1×ET-0 group. Within both GSH supplemented and control groups, the amplitude of lateral head displacement (ALH) is highest (P<0.05) in the ET-0 group. The percentage of live spermatozoa quadratically decreases and the percentage of dead sperm quadratically increases in response to graded levels of ET (P<0.01). The highest plasma membrane functionality is also noted in the GSH-1×ET-0 group (P<0.05). Mitochondrial membrane potential quadratically decreases in response to increasing levels of ET (P<0.05). CONCLUSION Generally, GSH supplementation to rooster sperm extender has some beneficial effects on post-thawed sperm motion characteristics, but does not positively interact with ET.