Abstract
This study investigated the effects of dietary lycopene supplementation on semen quality, testicular histology, antioxidant capacity, and reproductive hormone levels in aging breeder roosters. A total of 96 roosters were randomly divided into four groups and supplemented with 0, 50, 100, and 200 mg/kg of lycopene for six weeks. Lycopene significantly improved semen volume, sperm concentration, motility, viability, and morphological parameters at all doses (P < 0.05). The 200 mg/kg group exhibited the highest semen volume by week 6 (0.44 mL, P < 0.05). Sperm concentration increased significantly in the 100 mg/kg group (P < 0.05), and motility was highest in the 200 mg/kg group by week 4 (92.08 %, P < 0.05). Testicular histology also showed significant improvement, with a notable increase in seminiferous tubule area at 200 mg/kg (0.11 mm², P < 0.01), while Leydig cell density followed a quadratic response, peaking at 100 mg/kg (44.60 cells/mm², P < 0.01). Plasma LH and testosterone levels peaked at 100 mg/kg, with significant increases of 12.81 % and 43.37 %, respectively (P < 0.01). Lycopene enhanced antioxidant capacity across seminal plasma, plasma, and testicular tissues, with significant increases in T-SOD, GSH-Px, and CAT activities (P < 0.05). MDA levels were significantly reduced, especially at 100 mg/kg (P < 0.01). Lycopene supplementation also improved mitochondrial function in sperm, as indicated by enhanced mitochondrial membrane potential at 100 mg/kg (P < 0.01) and reduced reactive oxygen species levels and sperm apoptosis (P < 0.05). In conclusion, lycopene supplementation, particularly at 100 mg/kg, significantly improves semen quality, testicular health, antioxidant capacity, and reproductive hormone levels in aging breeder roosters, with potential applications in enhancing reproductive performance.