Effect of N-acetyl-d-glucosamine, and glycerol concentration and equilibration time on acrosome morphology and motility of frozen-thawed boar sperm

A series of experiments were conducted to determine the effect of N-acetyl-d-glucosamine, glycerol concentration and equilibration time for the freezing of boar spermatozoa in 5 ml maxi-straws. The optimum final glycerol concentration in the diluent with 0.05% N-acetyl-d-glucosamine in the first diluent was 2–3% and the optimum glycerol equilibration time was 2–3 h. In conclusion, we recommend the first diluent containing 11% lactose hydrate, 20% egg yolk and 0.05% N-acetyl-d-glucosamine in 100 ml distilled water, and the second diluent containing 11% lactose hydrate, 20% egg yolk, 4% glycerol and 1% orvus es paste for the diluents of boar sperm freezing. Also, we found out that 0.05% soluble N-acetyl-d-glucosamine was the optimum concentration in the first diluent and a concentration of 0.05% soluble N-acetyl-d-glucosamine significantly enhanced the cryopreservation of boar spermatozoa.