Multi Component Probiotic Blend Elevates Growth Efficiency and Reduces Nitrogenous Wastes in Intensive Tilapia Farming

Probiotic-based functional feeds are increasingly adopted in intensive aquaculture, requiring species- and dose-specific validation, especially for the Nile tilapia systems. This 70-day pond trial evaluated five isonitrogenous diets supplemented with a multi-component probiotic blend (Bacillus subtilis, Bacillus licheniformis, beta-glucan, and mannan-oligosaccharides) at concentrations of 0, 25, 50, 75, and 100mg per 100g diet. Monosex Nile tilapia fingerlings (initial weight ≈24.7± 0.16g) were used under controlled concrete-pond conditions to assess growth performance, feed utilization, digestive enzyme activities, gut pathogenic bacterial loads, serum biochemistry, somatic indices, immune indices, antioxidant enzymes, and water quality. Moderate probiotic inclusion (50– 75mg 100g⁻¹) significantly improved growth performance indices and survival rate, with regression indicating an optimum near 60mg 100g⁻¹ for digestive enzyme activity. Water quality also improved, showing elevated dissolved oxygen and reduced ammonia and nitrite. Intestinal pathogenic loads (E. coli, Vibrio, Salmonella, Shigella, Aeromonas spp.) declined markedly at 50–75mg 100g⁻¹, indicating enhanced microbial homeostasis. Furthermore, moderate doses enhanced physiological status: hematological profiles increased, while serum cortisol, ALT, and AST decreased. Innate and adaptive immune markers (lysozyme, IgM, C3) and antioxidant enzymes were elevated at 25– 50mg 100g⁻¹. Body composition reflected improved metabolic efficiency with higher crude protein and lower lipid. Collectively, dietary inclusion around 50– 75mg 100g⁻¹ provides integrative gains in performance, health, and environmental quality, strongly supporting probiotic-functional feeds as a practical tool for sustainable the Nile tilapia aquaculture.