Black soldier fly larvae (BSFL) meal is increasingly recognized as a sustainable and eco-friendly protein source in aquaculture, yet there is limited information on its use in feed production for Heterobranchus bidorsalis. This study aimed to evaluate the haemato-immunological responses and histomorphological changes in H. bidorsalis fed with differently processed BSFL meal. BSFL were harvested a greenhouse set up in the University of Ibadan Fish farm. The larvae were processed by sun drying and oven drying, and then used to formulate diets with inclusion levels of 0%, 25%, 50%, 75%, and 100%. A total of 300 H. bidorsalis (average weight: 10.5g) were divided into five treatments, with three replicates for both processing methods.
The highest white blood cell (WBC) count (18.93±1.52) was observed in the BSFL 75 group, while the lowest (15.95±1.52) was in BSFL 100. The highest platelet count (263±26.03) was recorded in the BSFL 50 group, and the lowest (204±26.03) in the control group (BSFL 0). Lymphocyte and Heterophil counts were highest in the control. Values for Aspartate aminotransferase (AST), Alkaline phosphatase (ALP) and Alanine aminotransferase (ALT) were significantly low in the control group (Table 1). The highest total protein (TP) levels (16.13±0.53) were found in BSFL 100, while the lowest (12.38±0.53) were in BSFL 25. Glutathione peroxidase (GPx) was highest (12.58±0.85) in the control group and lowest (9.26±0.85) in BSFL 75. There were no alterations observed in the kidneys of fish fed either sun-dried or oven-dried BSFL meal. However, varying fat deposit levels and congested sinusoids were noted in the kidneys of fish fed the 100% sun-dried BSFL diet, likely due to the high-fat content of the BSFL meal (Table 2).
Overall, this study demonstrates that both processing methods of BSFL meal improve the haematological parameters of H. bidorsalis without negatively affecting the histopathology of the kidney and liver.