Nutritional Implications of Substituting Soybean Meal with Azolla Powder on Growth Performance, Feed Efficiency, Body Composition, Blood constituents, and Economic Aspects in Nile Tilapia Fingerlings (Oreochromis niloticus)

Abstract

This experiment evaluated the effects of replacing soybean meal with Azolla powder (AP) at levels of 0, 25, 50, 75, and 100% in the diet, equivalent to 0, 10, 20, 30, and 40% of the total feed formulation (D1, D2, D3, D4, and D5, respectively). A total of 150 fish with an average initial weight of 15.5 ± 0.799g were distributed into 15 aquariums (10 fish each). The results indicated that AP contained
20.01% CP, 14.32% CF, 3.24% EE, 3792 kcal/kg DM GE, and 264.71 kcal/kg DM ME. All experimental diets were iso-caloric and iso-nitrogenous. Growth parameters such as FW, TBWG, ADG, SGR, and RGR improved, particularly in the 25% and 50% AP groups. Survival was 100%, and no mortality was observed. Feed intake, FCR, protein intake, and PER increased significantly (P<0.05). Hematological parameters improved, while liver enzymes, glucose, and lipid profiles decreased. Fish body composition analysis showed increased moisture, CP, and ash contents, while DM, OM, EE, and energy contents decreased. Energy retention and PPV% improved significantly (P<0.05). Additionally, feed costs were reduced, with optimal Azolla inclusion levels between 10-20%, corresponding to the replacement of 25-50% of soybean meal.