Functional plant-based feed additives for shrimp: evaluating the role of phytochemicals from tropical leaves on growth, feed efficiency, and disease resistance in P. monodon

Plant‐based functional feed additives represent a green alternative to antibiotics in shrimp aquaculture, but little comparative data are available on tropical leaf diets. Post-larvae Penaeus monodon (PL 15–20; 30 shrimp tank¹) were reared for 49 days on the basal diet alone and the identical diet supplemented with 1, 2.5, or 5% papaya Carica papaya, guava Psidium guajava, and sweet potato Ipomoea batatas leaf powder (nine diets). Growth, feed utilization, survival, and non-specific immunity (hemocyte count, clotting time) were recorded. Disease resistance was challenged in a 14-day immersion test with Vibrio parahaemolyticus (10⁷ CFU mL⁻¹). Guava 5% showed the highest final weight (4.43 ± 0.013 g), specific growth rate (8.49 ± 0.04% day⁻¹), and the lowest FCR (0.89 ± 0.02). Guava 2.5% showed the lowest cumulative mortality (30%) when challenged with bacteria and maintained the maximum total hemocyte count (~5 × 10⁷ cells mL⁻¹). Papaya 5% promoted enhanced weight gain (8.30 ± 0.03% day⁻¹) and survival (88%), and sweet potato effects were moderate. Water quality parameters were kept within optimal ranges during treatments. Inclusion of 2.5–5% guava leaf powder in diets improved growth efficiency and natural immunity of P. monodon markedly over papaya and sweet potato leaf meals. Therefore, tropical guava leaves symbolize a low-cost, locally available functional food that can potentially reduce shrimp aquaculture’s reliance on antibiotics.