Effect of cooling rate on quality of frozen yak semen during cryopreservation

Abstract

A study was conducted to record the suitable cooling rate during yak semen cryopreservation. Both fast and slow cooling rates have some adverse effect during semen processing, which may vary with species also. In the present study, the yak semen was cooled using three cooling rates viz., @ 1 °C/2 minutes, @1 °C/3 minutes and @1 °C/4 minutes. The post-thaw values for these cooling rates obtained were 42.50 ± 2.68, 51.50 ± 2.15 and 47.00 ± 2.67; 57.40 ± 1.79, 60.55 ± 1.98 and 57.35 ± 1.82; 46.10 ± 1.21, 52.35 ± 1.48 and 50.55 ± 1.50; 14.00 ± 0.29, 12.30 ± 0.25 and 13.30 ± 0.36 per cent for sperm motility, live sperm, host-reacted sperm and total incidence of acrosomal changes respectively and 14.24 ± 0.80, 13.86 ± 1.03 and 10.47 ± 0.70 IU/l and 13.54± 0.70, 11.68 ± 0.96 and 11.33 ± 1.05 IU/l for extra cellular release of ALT and AST activity respectively. In conclusion, a cooling rate of 1 °C/3 minutes (in 1.5 hrs) may be more effective for cryopreservation of yak semen.