Effect of cricket meal on transcriptional response of immune-related genes in blue Tilapia (Oreochromis aureus)

The rapid growth of aquaculture and a shortage of fishmeal have increased the demand for quality and cost-effective protein sources for aquafeeds. Recently, cricket meal (Acheta domesticus) has gained interest due to its high protein content, cheap production costs and lower environmental impacts than those of conventional protein sources. Worldwide, tilapia (Oreochromis aureus) is one the most commercially important species produced by aquaculture, yet the increasing costs of feed and diseases endanger its sustainability. Therefore, the aim of this research was to evaluate the effects of replacing fishmeal with cricket meal (0, 20, 40, 60 and 80%) on the final weight and survival of and the expression of interleukin 1β (IL-1β), interleukin 8 (IL-8), tumor necrosis factor (TNF) and immunoglobulin G (IgM) in tilapia. For this purpose, 200 tilapia fingerlings (2.00 ± 0.9 g) were randomly distributed into 20 tanks (250 L each). Each diet was randomly divided into four replicates (with 10 tilapia per tank). The tilapia were fed to satiation, with an initial ration of 0.3% of their biomass divided into three rations during the day (8:00, 12:00 and 16:00 h) for 10 weeks. At the end of the trial, blood samples were taken from four tilapias ffrom each replica, pooled and treated with Trizol for RNA extraction. cDNA was synthesized using oligo dT and the IMPROM-II system. The transcriptional response was measured based on immune-related genes and β-actin as the control. There were no differences in the final weight of the tilapia fed the control and 20% diets. However, their growth decreased significantly with the increasing inclusion of cricket meal in their diets. The survival did not change among the groups. Overall, the inclusion of 40-80% cricket meal increased the expression of all genes. In conclusion, cricket meal can be used to replace fishmeal at a level of up to 20% without affecting growth, whereas increasing its inclusion improves immune-related gene expression.