Cryopreservation with α-tocopherol and Sephadex filtration improved the quality of boar sperm.

The objectives were to evaluate postthaw sperm quality and the response to an inducer of in vitro sperm capacitation in boar sperm, cryopreserved with (T) or without (C) α-tocopherol. Boar sperm frozen in 0.2-mL pellets were thawed and washed (W) or selected by three methods: Percoll discontinuous gradient (PS) or Sephadex (Sigma-Aldrich, St. Louis, MO, USA) (neutral [S] or with ion exchange [S+IO] columns). All separation methods enhanced sperm motility, plasma membrane integrity, and functionality and acrosome integrity for both C and T samples (P < 0.05). The best results were obtained with S and ionic Sephadex column. There was a decrease (P < 0.05) in capacitation-like changes in C samples separated with Sephadex (W: 19 ± 0.9%, PS: 22 ± 2.5%, S: 17 ± 1.2%, and S+IO: 17 ± 2.0%). Cryopreservation with α-tocopherol decreased (P < 0.05) the percentage of cryocapacitated sperm (W: 14 ± 0.7%, PS: 14 ± 1.0%, S: 13 ± 1.0%, and S+IO: 14 ± 0.9%) compared with C samples, without differences among selection techniques. Freezing with α-tocopherol and subsequent selection decreased lipid peroxidation (W: 20.79 ± 2.64 nmol thiobarbituric acid reactive substances (TBARS)/10(8) sperm; PS: 13.15 ± 2.39 nmol TBARS/10(8) sperm; S: 13.20 ± 2.18 nmol TBARS/10(8) sperm, and S+IO: 13.62 ± 2.76 nmol TBARS/10(8) sperm), with respect to washed and selected C samples (W: 37.69 ± 5.34 nmol TBARS/10(8) sperm, PS: 25.61 ± 5.85 nmol TBARS/10(8) sperm, S: 19.16 ± 3.28 nmol TBARS/10(8) sperm, and S+IO: 22.16 ± 6.09 nmol TBARS/10(8) sperm). In vitro capacitation levels were significantly higher for neutral Sephadex-selected T samples in comparison with C and unselected samples. These results were confirmed with a follicular fluid-induced acrosome reaction. In conclusion, cryopreserved sperm with α-tocopherol and subsequent Sephadex selection, improved postthaw quality and functionality of boar sperm, which could be useful for assisted reproductive techniques.