Effect of post-thaw thermal resistance test on motility, membrane integrity and migration capacity of sperm in Gir bulls

Abstract

Incubation test assesses the livability of spermatozoa in female reproductive tract and thereby the longevity of the sperms. Indirectly, it assesses the freezing injuries occurred to sperms during the deep freezing process. The period spent after thawing and before insemination may affect the quality and fertility of post-thaw semen. The frozen semen was thawed at 37°C for 30 sec and taken into a small sugar tube and incubated in the water-bath at 37°C for 0 h, 15 min, 30 min, 45 min and 60 h and per cent post-thaw motility (PTM%), hypo-osmotic swelling test (HOST%) and cervical mucus penetration test (CMPT – mm) were carried out. The PTM declined from 54.33±1.18% at 0 h to 53.00±1.17% – 15 min, 47.33±1.08% - 30 min, 43.33±1.05% - 45 min and 35.67±1.27% at 60 min. HOST reduced from 52.53±1.53% at 0 h to 51.07±1.45%- 15 min, 42.67±1.82%- 30 min, 33.80±2.36%- 45 min and 23.60±1.10% at 60 min. Similarly, CMPT reduced from 28.00±1.23 mm at 0 h to 8.27±0.56 mm at 60 min. The overall post-thaw motility, HOST and CMPT at 0 h and 15 min were significantly higher than 30 min, 45 min and 60 min in Gir bulls. Post-thaw motility, hypo-osmotic swelling test and cervical mucus penetration test remain unaffected up to 15 min post-thaw incubation while there is significant decline in at 30, 45 and 60 min, which indicated that increasing post-thaw incubation duration affects post-thaw motility, cell membrane permeability and cervical mucus penetration ability of spermatozoa which may affect fertility.