Abstract
BACKGROUND AND AIM: Enhancing poultry reproductive performance is essential for improving productivity and addressing protein shortages in developing regions. Yoruba ecotype chickens (YECs) are resilient but limited in commercial potential due to small body size and low egg yield. This study assessed the fertilizing potential of YEC × Sussex (SS) crossbred cocks by integrating conventional reproductive morphometrics with seminal plasma metabolite profiling to identify potential biomarkers of sperm quality. MATERIALS AND METHODS: Thirty 24-week-old YEC × SS cocks (2842.86 ± 137.33 g) were evaluated over 28 days. Semen was collected through abdominal massage, and semen volume, sperm concentration, and testosterone levels (enzyme-linked immunosorbent assay) were recorded. Testicular and epididymal morphometrics, densities, and sperm reserves were measured. Seminal plasma metabolites were analyzed using high-performance liquid chromatography-mass spectrometry. Pearson correlations and linear regression models were applied to predict testosterone concentration from semen and morphometric traits. RESULTS: The left testis was heavier (8.00 g) and larger in volume (12.77 mL) than the right (6.75 g; 1.35 mL). Spermatozoa reserves averaged 0.20 × 10(9), with a strong positive correlation with testis volume (r = 0.998, p < 0.01) and a moderate negative correlation with daily sperm production (r = -0.585, p < 0.01). Testosterone concentration prediction from live weight, semen volume, and sperm concentration achieved high accuracy (R(2) = 0.829). Thirteen seminal plasma metabolites were identified, including ascorbic acid, quercetin, epicatechin, citric acid, and procyanidin B2 - compounds linked to antioxidant defense, energy metabolism, and sperm viability. CONCLUSION: YEC × SS crossbred cocks exhibit favorable reproductive morphometrics, strong correlations between testis volume and sperm reserves, and a metabolite profile enriched in fertility-enhancing antioxidants. Predictive models using basic semen traits can reliably estimate testosterone levels, while identified metabolites have potential as biochemical markers for breeding selection. Integrating morphometric and metabolomic profiling can refine breeding strategies, improve artificial insemination outcomes, and enhance the genetic improvement of local poultry breeds.