The immune functionality in fish requires a considerable support through diet for keeping the non-specific and specific components of immunity ready for combating any disease-causing agent. Fish become much more vulnerable to diseases when fed with low quality diet. Moreover, the head kidney in fish is an active site of lymphoid cell generation and endocrine functionalities. The regulation of the expression of the immune genes in the head kidney plays significant role in the regulation of inflammatory responses, antibody production, and cytoskeletal functions.
This study evaluated the effect of feeding Nile tilapia (47.0 g) with three commercial diets with and without probiotics for 213 days on the expression of some immune genes in the head-kidney such AS fish immunoglobulin (IgM), interleukin for cell inflammatory response (IL-β1), tumor necrosis factor protein (TNF-α), antiviral protein (Mx), and skeletal muscle protein (β-actin). For confidentiality, the control diets were coded D1 (35.3% protein), D2 (34.4% protein, and D3 (13.4% protein) and their corresponding probiotic diets were labelled D4, D5, and D6. Each diet was triplicated in 0.43 m3 tanks. Data is presented as cycle threshold (Ct) values which is the number of PCR cycles for fluorescent signals to cross the threshold levels.
One-way ANOVA indicated significant up regulation of the immune genes due to diet supplementation with the probiotic preparations. Probiotic supplementation significantly influenced the Ct values for β-actin, Mx, TNF-α and IL-I β. Regulation pattern of different genes is presented Table 1. Two way ANOVA showed immune genes to be significantly affected by diet type and probiotics with a two-way interaction between diet and probiotics.
It can be concluded that the up regulation of immune genes in the head-kidney due to probiotic supplementation would depend on the quality of the commercial diet used.