Pre-freezing and post-thawing quality of boar sperm for distinct portions of the ejaculate and as a function of protein bands present in seminal plasma

This study evaluated pre-freezing and post-thawing boar sperm quality in distinct portions of the ejaculates and identified protein bands potentially related to boar sperm tolerance to freezing. The sperm-rich portion of the ejaculate was fractioned in: the first 10 mL (P1); and its remaining volume (P2). Those portions were frozen and the bands present in both portions were evaluated by one-dimensional electrophoresis. Inter- and intra-boar ANOVA evaluated how the presence of bands related to pre-freezing and post-thawing sperm motility and membrane integrity and to post-thawing acrosome integrity. Post-thawing sperm motility, membrane integrity and acrosome integrity were greater for P1 than for P2 (P < 0.05). The presence of the 19 kDa band was associated with improved pre-freezing sperm motility and membrane integrity, but with reduced post-thawing acrosome integrity (P < 0.05). The presence of the 44 kDa band was associated with reduced post-thawing sperm motility and acrosome integrity (P < 0.05). Post-thawing acrosome integrity was enhanced when the 80 kDa band were present (P < 0.05). Reduced pre-freezing sperm membrane integrity and post-thawing sperm motility were associated to the presence of the 100 kDa band (P < 0.05). The presence of the 18 kDa band in P2 was associated with reduction in both post-thawing sperm motility and membrane integrity (P < 0.05), but such an effect was not observed in P1 (P > 0.05). Thus, sperm from P1 presented greater tolerance to freezing than sperm from P2 and the 18, 19, 44, 65, 80 and 100 kDa bands may be potential markers for boar sperm tolerance to cryopreservation.