Influence of sexual maturity on sperm quality in Duroc boars

The objective of this study was to evaluate sperm quality of Duroc boars during sexual maturation and examine whether these parameters were related to metabolites in semen. Ejaculates were collected longitudinally from 28 Duroc boars at approximately 7 months of age (Age 1), 6 weeks later (Age 2) and 12 weeks later (Age 3). Motility characteristics, acrosome integrity, and viability were assessed on collection day and after five days storage at 18°C using computer-assisted sperm analysis and flow cytometry, while DNA fragmentation was measured on day five. Amino acid and amine concentrations in semen were measured by liquid chromatography-mass spectrometry and correlated with sperm quality parameters. Motility, rapid progressive motility, and acrosome intact live sperm increased significantly (adj P < 0.05) with boar maturation. Mature boars (Age 2 and Age 3) maintained superior sperm quality compared to younger boars after storage. The DNA fragmentation index was low in all samples but declined significantly from 1 % at Age 1 to 0.64 % at Age 3 (adj P < 0.05). Correlation analysis showed significant relationships between sperm quality and specific metabolites. Cystine, glutamate, aspartate, choline and taurine were inversely correlated with progressive and rapid progressive motility, while showing positive correlation with rapid non-progressive motility. These findings demonstrate that sperm quality continues improving beyond initial reproductive ability, especially between Age 1 and Age 3, with improvements in motility, viability, chromatin stability, and storage resilience. The observed relationships between metabolites and sperm quality parameters provide insights into biochemical mechanisms underlying sperm functionality during sexual maturation.