Precursor A-Kinase Anchor Protein 4 as a Predictive Biomarker of Post-Thaw Semen Quality in Goats

The evaluation of sperm proteins has emerged as a promising approach to predicting semen quality across animal species. This study investigated the relationship between post-thaw concentrations of precursor A-kinase anchor protein 4 (proAKAP4) and objective sperm quality parameters in goats. Semen was collected from 16 adult goats (Boer, n = 8; Anglo-Nubian, n = 8) and frozen using a standardized protocol with OptiXcell (IMV Technologies, l'Aigle, France) extender (n = 5). After thawing, proAKAP4 concentrations were measured with an enzyme-linked immunosorbent assay (ELISA), while sperm motility and kinematics were assessed with computer-assisted analysis (CASA), and viability, plasma membrane integrity, acrosome integrity, and mitochondrial activity were evaluated using flow cytometry. Samples were grouped according to low, medium, or high proAKAP4 levels for comparison, and correlations with sperm parameters were examined. The results showed that semen with higher proAKAP4 concentrations had significantly greater total and progressive motility, more favorable kinematic values, and improved viability, plasma membrane integrity, and mitochondrial function (p < 0.05), whereas acrosome integrity was not influenced (p > 0.05). The average post-thaw proAKAP4 concentration was 38.66 ± 1.11 ng/10⁶ sperm, and no differences were observed between Boer and Anglo-Nubian breeds (p > 0.05). These findings indicate that proAKAP4 is strongly associated with multiple sperm functional traits and may serve as a reliable biomarker for assessing post-thaw semen quality in goats.