Effects of dietary Hericium erinaceus powder on growth, hematology, disease resistance, and expression of genes related immune response against thermal challenge of Nile tilapia (Oreochromis niloticus)

From the paper

Abstract

Functional feed additives have been promising possibilities for improving fish immune function. The present study attempts to investigate the effect of dietary Hericium erinaceus (HE) supplementation on growth performance, hematology, disease resistance, and expression of genes related immune response against thermal challenge in Nile tilapia. Four isonitrogenous and isolipidic diets were prepared: a control diet without HE supplementation (HE0), HE supplementation at 5 g/kg (HE5), 10 g/kg (HE10), and 20 g/kg (HE20). Each diet was fed to quadruplicate groups of Nile tilapia (9.96 ± 0.01 g/fish) to apparent satiation two times daily for 10 weeks. The dietary HE supplementation promoted protein productive value with a quadratic effect (P = 0.002) although it had no significant effect on other growth and feed utilization parameters (P > 0.05). In addition, the dietary HE supplementation linearly increased red blood cell count, hematocrit, and hemoglobin content (P ≤ 0.001) and quadratically increased the contents of protein and albumin, as well as the alkaline phosphatase activity (P 0.05), but significantly decreased HSP70cB1 transcripts and plasma cortisol levels after thermal stress challenge (P < 0.05). Therefore, it is suggested that HE at 10 g/kg can be used as a feed additive that enhances the immunity response, reduces the risk of infectious diseases caused by S. agalactiae, and improved thermal stress resistance in Nile tilapia culture.