Evaluation of Soybean Meal Substitution with Padina australis on Growth Performance and Feed Utilization Efficiency of Nile Tilapia (Oreochromis niloticus)

Abstrak

The increasing cost and sustainability concerns associated with conventional plant-protein ingredients have intensified the search for locally available functional feed materials for Nile tilapia. This study evaluated the effects of partially replacing soybean meal with the brown macroalga Padina australis meal on growth performance, feed utilization, and survival of Nile tilapia (Oreochromis niloticus). A 42-day feeding trial was conducted using a completely randomized design with four dietary treatments and three replicates. The treatments were TP-0 (30 g soybean meal; 100% soybean meal), TP-7.5 (7.5 g P. australis meal + 22.5 g soybean meal), TP-15 (15 g P. australis meal + 15 g soybean meal), and TP-22.5 (22.5 g P. australis meal + 7.5 g soybean meal). Fish with an initial body weight of 10.53 ± 0.34 g were stocked at six fish per aquarium and fed at 5% biomass day⁻¹. The measured variables included survival rate, weight gain, specific growth rate, feed intake, feed conversion ratio, and feed efficiency. Dietary treatment did not significantly affect any measured parameter (P > 0.05). Nevertheless, TP-7.5 produced the most favorable biological response, as indicated by the highest weight gain (6.21 ± 1.09 g), the highest specific growth rate (2.28 ± 0.21% day⁻¹), the lowest feed conversion ratio (3.75 ± 0.37), and the highest feed efficiency (26.81 ± 2.48%). These findings indicate that P. australis meal can be considered a low-inclusion functional ingredient in Nile tilapia diets, although higher inclusion levels require further nutritional optimization through balanced protein and energy formulation.