ABSTRACT Boar semen cryopreservation is crucial for the porcine industry. The two‐step (S2) is currently used for cryopreservation of boar semen. In this method, a cryoprotectant is added at 4°C to reduce its toxicity. Another method is the one‐step (S1), which is easier, cheaper and reduces the need for equipment, but may increase the toxicity of cryoprotectant. This study compared S1 and S2 equilibration protocols, evaluating post‐thaw total motility, viability, motion parameters, membrane integrity, antioxidant indicators, apoptosis and related gene expression. Results showed S2 had higher motility ( p < 0.05), while S1 had greater average path velocity ( p < 0.05), better plasma membrane integrity ( p < 0.05), lower malondialdehyde (MDA) ( p < 0.01), higher total antioxidant capacity (T‐AOC) and catalase (CAT) ( p < 0.01), lower superoxide dismutase (SOD) ( p < 0.05) and reduced apoptosis ( p < 0.05). S2 had higher Caspase‐9, Bax and SOD‐2 expression ( p < 0.05). S1 shows superiority in membrane protection, antioxidant capacity and anti‐apoptosis, despite slightly lower motility. It is a promising method for large‐scale use with further refinement to enhance post‐thaw motility.
Zhang et al. (Sun,) studied this question.