Synergistic Effects of Elevated Water Temperatures and Dietary Dried Yeast on the Growth Performance and Fed Utilization of the Nile Tilapia (Oreochromis niloticus)

This study evaluated the effect of dietary dried yeast supplementation on growth performance, feed utilization, body composition, energy retention (%), and protein productive value (PPV%) of the Nile tilapia (Oreochromis niloticus) fries reared at different water temperatures. A total of 180 fries (initial mean weight 146.17 ± 0.845 g/tank; 10 fish per tank; individual initial weight 14.617 g/fish) were randomly distributed into 18 aquaria. Diets were formulated to be isocaloric and isonitrogenous, with dried yeast added at 1.2% (12 g/kg) in groups G4–G6 for 75 days. Water temperatures were maintained at 28 °C (G1, G4), 31 °C (G2, G5), and 34 °C (G3, G6) during the last 15 days of the trial. Fish fed yeast-supplemented diets exhibited higher final body weight, body weight gain, daily growth rate, specific and relative growth rates, feed intake, and protein intake compared with control groups. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly improved (P < 0.05). Proximate body composition, including crude protein, ether extract, and gross energy, was significantly influenced by yeast supplementation. Both energy retention (%) and PPV% increased significantly in yeast-fed groups. Economic evaluation indicated net improvements in feeding cost (%) of 0.00, 7.90, 0.48, 22.24, 23.24, and 24.53 for groups G1–G6, respectively. In conclusion, supplementation of dried yeast in diets of Nile tilapia fries under elevated water temperature regimes enhanced growth performance, improved nutrient utilization, reduced feed cost, and increased resilience to thermal stress. These findings support the use of dried yeast as a functional feed additive, contributing to more sustainable aquaculture practices.