Determination of the effects of dietary silver nanoparticles biosynthesized with green walnut husk extract on the health of rainbow trout (oncorhynchus mykiss, walbaum, 1792)

This study aimed to determine the effects of silver nanoparticles (AgNP) obtained by biosynthesis using green walnut shell (YCK) extract on growth, histology, immune system, antioxidant activity and disease resistance against Aeromonas sobria in rainbow trout. Fish with an average weight of 10 g were fed with diets containing 0 µg/Kg (Control), 10 µg/Kg and 15 µg/Kg green walnut shell extract and 10 µg/Kg and 15 µg/Kg green synthesized AgNP for 30 days. After the feeding trial, growth indices were found to be statistically higher in the group fed with 10 µg/Kg AgNP. In immunological parameters, no statistically significant difference was observed in serum total protein levels in all groups. Serum lysozyme activity was higher than control, but no statistically significant difference was detected between the extract and AgNP groups. IgM levels were highest in the group fed with 10 µg/kg AgNP. In the antioxidant activity levels obtained from liver tissues, significantly higher CAT and MDA levels were observed in fish in the 10 µg/kg AgNP group compared to all other groups. No tissue damage was detected in all groups in liver and kidney histology. In gene expression, β-actin was used as the reference gene, IL-1b, TNF-a, TGF-b and IL-10 as the target gene. When the expression levels of all genes were examined between the groups, it was seen that the 10 µg/kg AgNP group was important in terms of immunity with a higher expression level than the other groups. At the end of the experiment, A. sobria LD60 dose of 108 cfu/ml 0.1 ml was applied intraperitoneally and the survival rate of fish fed with 10 µg/kg AgNP was observed as 83%. As a result, it is thought that 10 µg/Kg AgNP dose has the potential to be used in improving fish health and preventing diseases in trout farming.