Effects of tamarind pulp powder supplementation on growth performance, haemato-immunological parameters, and immune-related gene expression in pacific white leg shrimp (Litopenaeus vannamei)
Background: Application of dietary phytobiotics against bacterial pathogens in shrimp farming is considered a promising alternative to antibiotics. Aims: The present study investigated the impact of tamarind pulp-powder (TPP) supplemented diets on growth, survival, immune responses, resistance to Vibrio harveyi, and immune gene expression in Litopenaeus vannamei. Methods: A 49-day feeding trial was conducted using L. vannamei (mean weight 5.60±0.45 g) fed with TPP-supplemented diets containing 0 (T0), 1 (T1), 5 (T2), and 10 (T3) g/kg diets at 3% body weight. Growth performance viz., net weight gain (NWG) and feed conversion ratio (FCR) were recorded on weekly basis and immune responses viz., serum protein (SP), Prophenoloxidase (PPO), and lysozyme (LZ) activities were analyzed at the end. A challenged test conducted for 96 h with V. harveyi (1×105 CFU/ml) to assess mortality. After the challenge test, enzymatic activities and immune genes viz., toll-like receptor and lysozyme were analyzed. Results: Shrimp fed with the T2 diet (5 g/kg TPP) showed significantly (P< 0.05) higher NWG, improved FCR, and survival compared to other groups. Total hemocyte count, SP, PPO, and LZ activities were significantly higher in T2 shrimp. Reduced levels of enzymatic activities and upregulated expression of immune-related genes were also observed in T2. During the challenge, T2-fed shrimp achieved the highest survival rate (86%), confirming enhanced resistance to V. harveyi. Conclusion: A dietary inclusion level of 5 g/kg TPP was found optimal for improving growth, immunity, and resistance against vibriosis in L. vannamei, highlighting its potential as a phytobiotic alternative to antibiotics in shrimp aquaculture.