Influence of Hermetia illucens meal dietary inclusion on the histological traits, gut mucin composition and the oxidative stress biomarkers in rainbow trout (Oncorhynchus mykiss)

Histopathological examination of liver, spleen and gut revealed no adverse effects following increasing levels of insect meal inclusions. Hermetia illucens consumption stimulated higher production of neutral than acidic mucins. Altered values of several antioxidant biomarkers indicated an unbalance of oxidative homeostasis in liver and mainly in kidney, linked to the feeding conditions. While lowering of glutathione peroxidase activity may reflect slight adverse effect of HI meals in both tissues, strengthening in levels of ethoxyresorufin O-deethylase, glutathione S-transferase and total glutathione may indicate the shielding of HI meals-mediated oxidative process. Although the administration of both inclusion levels of insect meal did not negatively affect the histological features in fish, the changes of oxidative stress biomarkers advise for an HI dietary inclusion lower than 20%.