Crude protein in diets for nile tilapia broodfish

Abstract

The effect of different levels of crude protein (32A, 32B, 36, 38, 44 and 50% CP; 3,500 kcal digestible energy) on Nile tilapia broodstock was assessed. After 30 experimental weeks (Sept./14 to Mar./15), 91.0% of eggs from fish fed 44% CP hatched and produced 16.4% more viable larvae than the treatment with 32% CP. Egg production and absolute fecundity were similar between treatments (p>0.05). Sperm motility, average path, straight line and curvilinear velocities showed satisfactory values with 44% CP, unlike 36% CP. Lower profitability was observed with 32% CP; profit increased as protein level upped. Statistically significant responses were not found for reproductive performance of females. Results were satisfactory for commercial-scale production as crude protein increased. The initial hypothesis was demonstrated for most parameters assessed in males, larvae growth and economic viability. Therefore, it is recommend the use of diets with 44% CP for Nile tilapia brood fish.