Enhancement of Reproductive Performance in Rabbit Bucks through Ethanolic Bitter Kola (Garcinia kola) Supplementation: A Dose-Response Study

Abstract

This study looked into how the ethanolic extract of Garcinia kola, commonly known as bitter kola, affects the semen quality and hormonal profile of rabbit bucks. A total of twenty-four sexually mature rabbit bucks, aged between 6 to 8 months, were randomly divided into four groups of six animals each, following a Completely Randomized Design. Group A was given distilled water as a control, while Groups B, C, and D received the ethanolic bitter kola extract at doses of 100, 200, and 400 mg/kg body weight, respectively, administered orally every 12 hours for eight weeks. Semen samples were collected at weeks 0, 4, and 8 using an artificial vagina, and blood samples were taken for hormonal assays using ELISA. Phytochemical analysis showed that the extract contained flavonoids, alkaloids, tannins, saponins, and steroids. The results indicated that the 200 mg/kg dose significantly enhanced semen parameters by week 8, including semen volume (0.74±0.21 mL compared to 0.59±0.14 mL in the control), sperm motility (73.6±8.9% vs 63.8±10.1%), sperm concentration (193±35×10⁶/mL vs 167±28×10⁶/mL), total sperm count (143±40×10⁶ vs 99±28×10⁶), sperm viability (78.2±8.7% vs 70.3±7.8%), normal morphology (80.8±6.2% vs 77.9±5.7%), membrane integrity (76.9±9.0% vs 73.1±8.2%), and semen pH (7.23±0.21 vs 7.09±0.18). Additionally, significant increases were noted in testosterone (2.46±0.37 ng/mL vs 1.89±0.30 ng/mL), luteinizing hormone (0.91±0.15 mIU/mL vs 0.74±0.12 mIU/mL), and follicle-stimulating hormone (0.59±0.10 mIU/mL vs 0.46±0.08 mIU/mL) levels. The 100 mg/kg dose showed some improvements, while the 400 mg/kg dose yielded no significant benefits, indicating a dose-dependent effect. These findings demonstrate that ethanolic extract of Garcinia kola at 200 mg/kg optimally enhances reproductive performance in rabbit bucks through improved semen quality and hormonal stimulation