EFFECTS OF THAWING RATE AND STRAW VOLUME ON POST-THAW QUALITY OF BOAR SPERM AS INFLUENCED BY FREEZING RATE AND CRYOPROTECTANT

This study aimed to evaluate the combinatorial effects (24 treatments) of different cryoprotectants (3% glycerol alone [G], 3% glycerol with 1% dimethylacetamide (DMA) [GD]), straw volume (0.5 and 5[Formula: see text]mL), freezing methods (dry ice or liquid nitrogen) and thawing methods on boar semen cryosurvival. Six semen samples were manually collected from two or three Duroc boars and pooled. A total of 24 treatments were applied to each batch of pooled semen. Post-thaw semen quality analysis was done to evaluate the combinatorial effects of the various factors. After thawing, the highest semen quality indicators were observed with treatment 9G (3% glycerol, dry ice, 0.5[Formula: see text]mL, 60 ∘ C/8[Formula: see text]s), followed by treatment with 8G (3% glycerol, dry ice, 0.5[Formula: see text]mL, 50 ∘ C/12[Formula: see text]s), 9GD (1% DMA with 3% glycerol, dry ice, 0.5[Formula: see text]mL, 60 ∘ C/8[Formula: see text]s) and 12G (3% glycerol, dry ice, 0.5[Formula: see text]mL, 60 ∘ C/8[Formula: see text]s). There were no significant differences ([Formula: see text]) among the four treatments in post-thawed sperm motility ([Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively) and sperm viability ([Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively). In conclusion, the combination of glycerol, low straw volume, low freezing rate and high thawing rate is suitable for cryopreservation of boar semen. In addition, a higher thawing rate could improve the drawbacks of freezing rate, cryoprotectant and straw volume on sperm cryosurvival.