Growth parameters, hematology, immunity, and relative expressions of TNF-α and IL-8 genes in rainbow trout (Oncorhynchus mykiss) fed a combination of turmeric (Curcuma langa) powder and black pepper (Piper nigrum)

Abstract

Abstract This research aimed to investigate the effect of turmeric powder (Curcuma langa) and black pepper (Piper nigrum) on growth parameters, blood, immunity, and the relative expression of immune-related genes in rainbow trout (Oncorhynchus mykiss). Rainbow trout (n = 450, average weight 24.95 ± 0.70 g) were fed with four levels (0, 0.25, 0.5, and 1% of diet) of three combined levels of turmeric (C) and black pepper (P) plants (30% C + 70% P, 50% P + 50% C, 70% C + 30% P) in 10 experimental treatments each with three repetitions for 60 days. Growth, hematological and serum biochemical parameters, liver enzymes, serum immune parameters and the expression of TNF-α and IL-8 genes were evaluated at the end of the period. Based on the results, the highest values of final weight, average daily growth, specific growth rate, and the lowest food conversion coefficient were reported at the 1% level with the 70% C + 30% P combination. Significant changes were also observed in red and white blood cell counts, hemoglobin, hematocrit, total protein, globulin, lysozyme activity, total immunoglobulin, and complement activity at the 1% level with 70% C + 30% P combination. The TNFα gene relative expression decreased significantly in all nutritional treatments with the two combined plants compared to the control. The IL8 gene expression increased significantly in fish fed with the 1% combination of the two plants (70% P + 30% C) compared to the other treatments. Based on the findings, the optimal values of the growth, blood, and immunity parameters mainly at the 1% diet level in the treatments fed with the C and P combination can result from the positive effect of these compounds on the growth performance and immunogenesis in rainbow trout fingerling.