TERRESTRIAL ANIMAL TESTES AS NATURAL ANDROGEN ALTERNATIVES FOR INDUCING MALE SEX REVERSAL AND ENHANCING GROWTH IN NILE TILAPIA

Abstract

The increasing demand for all-male Nile tilapia (Oreochromis niloticus) stems from their superior growth and market preference. However, reliance on synthetic hormones such as 17α-methyltestosterone (MT) raises concerns about health risks, production costs, and environmental impact. This study assessed the efficacy of natural androgen sources from bull (Bos indicus), boar (Sus domesticus), and buck (Capra hircus) testes in inducing sex reversal, growth, and feed utilization in O. niloticus fry over 90 days. Four diets were formulated: T1 with 0.06 g MT/kg feed (control), T2 with 25 g bull testes/kg, T3 with 25 g boar testes/kg, and T4 with 25 g buck testes/kg. Proximate compositions were comparable across diets (crude protein 36.18–36.52%; lipid 7.11–7.23%). Water quality parameters remained optimal (temperature 27.1–27.6°C; dissolved oxygen 5.93–6.15 mg/L; pH 7.2–7.4). The highest final mean weight in the MT group (T1) (7.52 ± 0.10 g), followed by bull (T2) (7.24 ± 0.12 g), buck (T4) (7.01 ± 0.08 g), and boar (T3) (6.89 ± 0.11 g) testes groups. Specific growth rate (SGR) was highest in T1 (2.83 ± 0.04% day⁻¹) and T2 (2.76 ± 0.05% day⁻¹), with feed conversion ratios (FCR) 1.38 ± 0.02 and 1.44 ± 0.03, respectively. Sex reversal efficacy significantly differed (p < 0.05) among treatments, with MT producing 97.6% males, bull testes 94.3%, buck testes 90.1%, and boar testes 88.5%. Survival rates were high (84.4–95.5%) and statistically similar across treatments. These findings indicate that homogenized bull testes represent a potent, economical, and safe natural androgen source for sustainable monosex male production in O. niloticus, reducing dependency on synthetic hormones.