The Interplay Between Trace Elements, Morphometry, and Semen Quality in Bucks During the Breeding Season

Breed-related differences in spermatological traits, morphometric characteristics and trace element status may influence reproductive performance in bucks during the breeding season.

This study aimed to comparatively evaluate spermatological characteristics, body and testicular morphometric traits, and trace element concentrations in blood serum and seminal plasma of Honamli and Hair bucks during the breeding season.

A total of 16 bucks (8 Honamli and 8 Hair), aged 2-4 years, were included. Semen samples were collected for spermatological evaluation, including mass activity, volume, pH, motility, concentration, plasma membrane and acrosome integrity (PMAI), viability and mitochondrial membrane potential. Seminal plasma was obtained by centrifugation for biochemical analysis. Blood samples were collected from the jugular vein after semen collection, centrifuged and the serum was separated. Trace element concentrations (Se, Zn, Cu, Ca, Mg, Fe and Co) were measured in blood serum and seminal plasma at the beginning and end of the study. Body, scrotal, and testicular morphometric measurements were also recorded.

Honamli bucks exhibited significantly higher sperm motility (p < 0.05), sperm concentration, PMAI and mitochondrial membrane potential compared with Hair bucks (p < 0.001), while no significant differences were observed in semen volume, pH, mass activity or viability (p > 0.05). Significant breed-related differences were found in body morphometric traits, including withers height (p < 0.01), rump height (p < 0.001), tail length (p < 0.001), nose length (p < 0.001) and ear length (p < 0.05). Only scrotal circumference differed significantly between breeds (p < 0.05). In blood, Ca, Mg, Zn, Se and Co showed significant time-dependent changes (p < 0.001), while Fe also changed over time (p < 0.01); breed effects were not significant (p > 0.05). Furthermore, Ca increased in both breeds (p < 0.001), Zn increased in Honamli and Hair (p < 0.01 and p < 0.05, respectively), Co decreased in both breeds (p < 0.01) and Se increased only in Hair (p < 0.001). Significant time × breed interactions were found for Fe and Cu (p < 0.05); Fe was higher in Honamli on the first day (p < 0.05) and decreased only in this breed (p < 0.001), whereas Cu increased only in Hair (p < 0.05). In seminal plasma, Se, Fe and Cu changed over time (p < 0.001), whereas Ca, Zn, Co and Mg remained unchanged (p > 0.05); breed and time × breed effects were not significant for any seminal plasma mineral (all p > 0.05). In addition, Se increased in both breeds (Honamli: p < 0.001; Hair: p < 0.05), while Fe and Cu decreased in both breeds (Fe: p < 0.01 and p < 0.05; Cu: p < 0.01 and p < 0.001, respectively).

Honamli and Hair bucks display distinct spermatological, morphometric and trace element profiles during the breeding season. These findings indicate that trace element dynamics strongly influence semen quality, suggesting their potential use as markers for sire selection and targeted reproductive management.