Analysis of ejaculate parameters and sperm morphology in roosters of initial laying strains

The aim of this study was to evaluate the influence of laying hybrid lines of domestic fowl (Gallus gallus f. domestica) and their age on ejaculate parameters in roosters. Parameters assessed included ejaculate volume, sperm concentration, total sperm count (TSC), percentage of normal spermatozoa, and sperm motility. Additionally, morphological defects were observed: defects of the acrosome, head, neck, tail, and immature spermatozoa. The study included 120 roosters of the Barred Plymouth Rock, Sussex Light, Rhode Island Red, and Rhode Island White laying lines. Ejaculate was repeatedly evaluated at the ages of 34, 43, and 52 weeks. The average ejaculate volume was 0.52 ml, sperm concentration 2.53 × 109 cm–3, motility 81.1%, and defect occurrence rates were as follows: acrosome defects 0.7%, head defects 3.0%, neck defects 2.4%, and tail defects 2.9%. A statistically significant effect (P < 0.01) of the line was observed for all parameters except tail defects. Statistically significant differences between age categories were confirmed for volume, sperm concentration, TSC, immature spermatozoa, and normal spermatozoa (P < 0.01), as well as for ejaculate volume, neck, and tail defects (P < 0.05). The volume, concentration and TSC reached significantly higher values at 43 weeks of age. The incidence of normal spermatozoa and immature spermatozoa was significantly lower at 34 weeks of age. The interaction of age and line was significant (P < 0.01) for sperm concentration, TSC, motility, head, tail, and normal spermatozoa. The highest values of volume, concentration, and TSC were observed in the BPR line, which also exhibited the lowest occurrence of head defects and immature spermatozoa. The RIR line showed a higher occurrence of sperm defects. Younger roosters (34 and 43 weeks of age) had higher ejaculate parameter values and a higher occurrence of sperm defects compared to the older ones.