Abstract
The present study was investigated the dietary administration of cassic acid (CA) on growth, innate immunity, transcription profiles of estrogen and follicle-stimulating hormones as well as lysozyme enzyme determined in Clarias gariepinus against Edwardsiella tarda. The weight gain (WG), protein efficacy ratio (PER), and feed conversion ratio (FCR) were significantly improved in infected fish fed dietary administration with CA at 5 and 10 mg kg−1 diets. The survival is higher (96.7% and 98.3%) in the infected groups fed at 5 and 10 mg kg−1 CA diets. The red (RBC) and white (WBC) blood cells, hemoglobin (Hb), and packed cell volume (PCV) was found significantly high in the infected fish feeding at 5 and 10 mg kg−1 CA diets. Total protein and albumin were significantly increased with 5 and 10 mg kg−1 CA diets among weeks 1–4 while the globulin and albumin: globulin ratio increased of these diet only after week 2. The phagocytic and respiratory burst activities were enhanced statistically the infected fish fed at 10 mg kg−1 CA diet group whereas the production of superoxide anion (SOA) and nitric oxide (NO) were significantly increased at 5 and 10 mg kg−1 CA diets. The lymphocyte proliferation and myeloperoxidase (MPO) activity were significantly high the infected fish when fed at 5 and 10 mg kg−1 CA diets after 2nd week whereas the alternate complement activity (ACP), generation of reactive oxygen species (ROS), and lysozyme activity (Lyz) were observed at 5 and 10 mg kg−1 CA diets among weeks 1–4. The accumulative mortality was 10% in infected fish fed at 1 and 5 mg kg−1 CA diets whereas 15% mortality found with 10 mg kg−1 CA diet. The highest levels of estrogen receptor alpha (ERα) mRNA expression found in gonad while the highest levels of follicle stimulating hormone-beta subunit (FSH-β) mRNA expression found in testis of the infected fish given at 5 and 10 mg kg−1 CA diets. The up-regulation of chick-type lysozyme (c-Lyz) mRNA was observed at 5 and 10 mg kg−1 CA diets after 2nd week while goose-type lysozyme (g-Lyz) mRNA was up-regulation amongst weeks 1–4 of these diets. The present study suggested that E. tarda challenged fish after feeding with 5 and 10 mg kg−1 CA diets did not affect growth and hemato-biochemical parameter, but it enhanced nonspecific immune system and improving ERα, FSH-β, c-Lyz, and g-Lyz mRNA expression in C. gariepinus against E. tarda.
•Better weight gain, PER and FCR found with rhein 5 mg and 10 mg diets.•High survival rate 96.7% and 98.3% observed with 5 mg and 10 mg diets.•SOA and NO production increased with 5 mg and 10 mg diets on weeks 2 and 4.•ROS production and lymphocyte proliferation increased with 10 mg diet on weeks 2 and 4.•Complement and MPO activities increased with 10 mg diet on weeks 2 and 4.