Protective effect of commercial prebiotic Immunogen on liver histopathological lesions of rainbow trout (Oncorhynchus mykiss) experimentally infected by Aeromonas hydrophila

Application of prebiotics is a promising way in aquaculture, as non-digestible food ingredients that improve host health by stimulating or limiting the growth of bacteria in the host gut. Aim of this study was to investigate the protective effect of dietary commercial prebiotic, Immunogen®, on liver histopathology lesions exposured to Aeromonas hydrophila infection in rainbow trout (Oncorhynchus mykiss). This study was performed on 180 healthy sub-adult rainbow trout (81.65±1.49g) under experimental condition in three groups. In the first group (control) and second group, fish were fed the basal diet and in the third group, the prebiotic Immunogen was added to basal diet (one control group and two trial treatments with three replicates). After 6 weeks feeding, two last groups were injected by Aeromonas hydrophila (untreated-infected and treated-infected groups). Histophatological results revealed that lesions such as necrotic hepatocyte, cytoplasmic vacuolation, nucleus degeneration and entera cellular edema within the untreated-infected group were more than treated-infected group administrated by Immunogen®. These findings suggested improved resistance of rainbow trout liver administrated by Immunogen® during bacterial infection.