A new test based on the hypotonic resistance and functional competence to evaluate the sperm quality, cryotolerance and in vitro fertilizing ability in pigs.

The present work aimed at setting a new test of boar sperm functional competence (SFCt) to determine the association with sperm in vitro fertilizing ability and cryotolerance. Three independent experiments were conducted. In the first experiment, a gage repeatability and reproducibility (R&R) study was carried out to determine the reliability of the SFCt. Following this, 1565 ejaculates were clustered on the basis of sperm membrane and acrosome integrity, total motility, morphology and membrane functional integrity. Two groups were obtained and their SFCt values were compared. In the second experiment, 45 ejaculates were classified into two groups based on cleavage rates after in vitro fertilization and the SFCt outcomes of the two groups were examined. In the third experiment, 45 ejaculates were cryopreserved and classified as with good (GFE) or poor freezability (PFE) based on their post-thaw sperm membrane integrity and total motility; the SFCt outcomes in liquid-stored semen were also compared. ROC curves were used to address the accuracy of the SFCt in each experiment. In the R&R study, the greater variability of the study was attributed to the differences between ejaculates (97.61%); SFCt values were significantly (P < 0.01) higher in the good than in the poor sperm quality group. Ejaculates with high cleavage rates showed significantly (P < 0.05) higher SFCt values than ejaculates with low cleavage rates. SFCt values of GFE before cryopreservation were significantly (P < 0.05) higher than those of PFE. The SFCt had a fair discriminatory value in all experiments. In conclusion, the SFCt is a useful and reliable test to evaluate the sperm quality and is also related to the sperm resilience to withstand freeze-thawing procedures. However, further studies evaluating blastocyst formation and AI trials with a large number of boars are needed to confirm the accuracy of this test.