Effects of dietary supplementation with taxifolin on reproductive performance in aging layer breeder roosters

This study aimed to investigate how dietary taxifolin (TAX) supplementation affected the reproductive hormone profile, testicular function, antioxidant status, and semen characteristics in aged breeder roosters. Ninety-six Jingfen No. 6 roosters (63 weeks old) were allocated to four dietary treatments containing different TAX levels for six weeks: 0 (control), 200, 400, or 600 mg/kg TAX. Roosters in the 200 mg/kg group showed the most notable enhancements in reproductive performance, including significant elevations in semen volume and sperm motility at weeks 2, 4, and 6. TAX supplementation enhanced sperm kinematic parameters, particularly straightness, linearity, curvilinear velocity, and average path velocity, and the 200 mg/kg group consistently demonstrated better performance than the other treatments. Histological examination revealed that supplementation with 200 mg/kg TAX effectively improved testicular structure and spermatogenesis. In contrast, higher TAX concentrations (400-600 mg/kg) induced vacuolization and impaired tubular development. Plasma testosterone and follicle-stimulating hormone levels peaked in the 200 mg/kg group, whereas luteinizing hormone (LH) levels peaked in the 400 mg/kg group. TAX supplementation markedly enhanced the antioxidant capacity in the plasma, liver, seminal plasma, and testes. Further analysis of gene expression showed the dose-dependent upregulation of genes associated with antioxidant activity (SOD1, SOD2, CAT, GPX1, and GPX4) and stimulation of the nuclear factor erythroid 2-related factor 2/mitogen-activated protein kinase (MAPK/Nrf2) signaling pathway, particularly at 400-600 mg/kg TAX. Collectively, the results suggest that providing 200 mg/kg TAX optimally enhances multiple key metrics in aged breeder roosters, including semen quality, testicular health, reproductive hormone secretion, and antioxidant defense.