Comparison of slow freezing and vitrification methods for Venda cockerel’s spermatozoa

An improvement in avian semen cryopreservation is essential and has the potential to improve the cryo-gene banking efficiency. This study compared two cryopreservation methods (slow freezing and vitrification) and the effect of different thawing/warming temperatures (5 ̊C, 25 ̊C and 41 ̊C) on Venda cockerel’s spermatozoa. Semen samples from Venda cockerels were diluted with modified Kobidil extender supplemented with 8% dimethyl sulfoxide. Semen from each ejaculate was stained with nigrosin/eosin for viability examination. The cryopreserved samples were either slow cooled in 0.25 mL straw or vitrified in a solid surface vitrification (SSV) device. Semen straw or cryovial was stored in liquid nitrogen container. The straw or cryovial with sperm was thawed or warmed at 5 ̊C, 25 ̊C and 41 ̊C and analysed by a ComputerAided Sperm Analysis (CASA). There was a significant difference in live/normal sperm between the semen donors. Cockerels spermatozoa cryopreserved by slow freezing (43%) and thawed at 5 ̊C had a significantly higher survival and motility rate compared to vitrification (2.5%) method. In conclusion, there was higher rate of live/ normal morphology sperm. Cryopreservation process reduces sperm motility and velocity rate regardless of cryoprevervation method and thawing or warming temperatures. However, slow freezing was a better method to maintain motility of spermatozoa following cryopreservation.