Effect of anthocyanin extract from Roselle,Hibiscus sabdariffa, calyx on haematological, biochemical and immunological parameters of rainbow trout,Oncorhynchus mykiss

Abstract

In the present study, rainbow trout, Oncorhynchus mykiss, (14.1 ± 0.08 g) were fed diets supplemented with different levels of Roselle anthocyanin extract (RE) to assess the fish immune, stress and haematological parameters. For this, four levels of RE including 0, 0.5, 1 and 1.5% were added to the fish diet for eight weeks. Then, growth performance, blood haematological, biochemical, immunological and hepatic expression of cytokine genes were investigated in all treatments. At the end of the experiment, the fish exhibited similar growth rate and survival (final weight: 91.4–96.7 g; feed conversion ratio: 0.75–0.80; specific growth rate: 3.11–3.21% d−1; survival: 100%). The results showed that there were no significant differences in plasma glucose, cholesterol, triglyceride, total protein, albumin, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and alkaline phosphatase levels among the treatments. Supplementation of the diets with 1% RE significantly increased RBC, haemoglobin, haematocrit, lysozyme, complement and WBC, compared with the control treatment. 1 and 1.5% RE significantly decreased plasma cortisol levels, compared with the control. All levels of dietary RE significantly up-regulated hepatic tumour necrosis factor-alpha gene expression, compared with the control treatment. 1 and 1.5% RE significantly up-regulated hepatic interleukin-1 beta gene expression, compared with the control treatment. 1.5% RE supplementation significantly down-regulated interleukin-10 gene expression, compared with the other treatments. In conclusion, dietary RE supplementation at 1% is beneficial for rainbow trout, as it mitigates stress and increases immune-related parameters.