Dose-Dependent Effects of Ethanolic Garlic (Allium sativum) extract on Sperm Motility and Morphology in Nigerian Indigenous Cocks

Abstract

We investigated the effects of ethanolic garlic extract supplementation on reproductive performance in Nigerian indigenous cocks. Twenty-four healthy cocks aged 21-32 weeks were randomly assigned to three groups: control (distilled water), low-dose (250 mg/kg body weight), and high-dose (500 mg/kg body weight) garlic extract administered daily for eight weeks. Semen quality parameters and serum reproductive hormones were evaluated at baseline, week 4, and week 8. Results demonstrated significant time-dependent improvements in sperm motility and morphology with garlic supplementation. In the high-dose group, progressive motility increased from 53.8% at week 4 to 55.1% at week 8 (compared to 48.2% and 47.5% in controls at weeks 4 and 8 respectively), representing 11.6% and 16.0% improvements over controls. Morphological defects decreased progressively from 11.2% at week 4 to 10.5% at week 8 in the high-dose group (versus 13.7% and 14.5% in controls), achieving a 27.6% reduction by week 8. Testosterone levels showed dose-dependent elevation: the high-dose group demonstrated 22.5% increase at week 4 (4.9 ng/mL) and 38.5% increase at week 8 (5.4 ng/mL) compared to controls (4.0 ng/mL and 3.9 ng/mL respectively). However, ejaculate volume, sperm concentration, viability, and gonadotropin levels (LH and FSH) remained unchanged throughout the study period. These findings suggest that garlic extract enhances reproductive performance primarily through androgenic stimulation and antioxidant mechanisms acting directly at the testicular level rather than through pituitary modulation. The 500 mg/kg dose proved most effective, offering a cost-effective natural alternative to synthetic fertility enhancers in commercial poultry breeding programs.