Dietary Houttuynia cordata leaf extract and meal enhances the immunity and expression of immune genes in Labeo rohita (Hamilton, 1822).

Abstract

A feeding trial was conducted to explore the effect of dietary Houttuynia cordata leaf extract (HCLE) and leaf meal (HCLM) on immunological responses and expression of interferon-gamma (IFN-γ) and tumour necrosis factor-alpha (TNF-α) gene in Labeo rohita fingerlings. Six isonitrogenous (350 g/kg CP) and isocaloric (17 MJ/kg DE) pu-rified experimental diets were formulated with Houttuynia cordata leaf extract and leaf meal comprising control, C (0 g/kg HCLE and HCLM), E2.5 (2.5 g/kg HCLE), E5 (5 g/kg HCLE), E10 (10 g/kg HCLE), M10 (10 g/kg HCLM) and M20 (20 g/kg HCLM). Labeo rohita fingerlings (3.37± 0.23 g) were distributed in six experimental groups in triplicates following the complete random distribution. Fish were fed twice daily with respective experimental diets for a period of 60 days. A significantly (p< .05) lower lactate dehydrogenase, malate dehydrogenase, superoxide dismutase and catalase activities were registered in supplemented groups compared with control group, while respiratory burst and lysozyme activities were significantly (p< .05) higher in E10 group compared with other experimental groups. Haemoglobin, total leucocyte count, total erythrocyte count and haematocrit values were significantly (p< .05) higher in E10 group. The expression of IFN-γ and TNF-α in both the kidney and liver was significantly up-regulated in leaf extract and meal supplemented groups with the highest expression in the fish of E10 group. Overall, these results suggest that the dietary supplementation of ethanolic extract of the Houttuynia cordata leaf at 10 g/kg level can enhance the immune response of L. rohita fingerlings.