Akademik Veri Yönetim Sistemi
Aquatic Research, cilt.9, sa.2, ss.129-147, 2026 (Scopus, TRDizin)
This study evaluated the effects of low-fat (LFD), high-fat (HFD), and quercetin-supplemented high-fat (HFD+Q; 0.2 g/kg) diets on the haematological responses, intestinal histomorphology/histopathology, and resistance to Lactococcus petauri infection in rainbow trout (Oncorhynchus mykiss). A total of 270 fish (initial mean weight: 38.37 g) were randomly distributed into three dietary groups with three replicates per treatment (30 fish per tank) and fed the experimental diets for eight weeks. At the end of the trial, haematological parameters were determined using an automated analyser; histomorphometric measurements (muscle layers, villus parameters, and goblet cell counts) and histopathological evaluations were performed on intestinal samples. Furthermore, an intraperitoneal challenge with L. petauri was conducted to evaluate disease resistance. The HFD group exhibited significant suppression of leukocyte profiles (WBC, LYM, MID, GRAN) and a downward trend in HGB/HCT and erythrocyte indices. This group also displayed intestinal alterations consistent with muscular layer irregularities, submucosal oedema, and loss of goblet cells. In contrast, the HFD+Q group maintained more balanced haematological parameters and intestinal barrier indicators, contributing to the recovery of mucosal defence by increasing goblet cell counts compared to the HFD group. In the challenge trial, the survival probability was significantly higher in the HFD+Q group. In conclusion, quercetin is a functional feed additive with the potential to enhance resistance to L. petauri infection by supporting haematological homeostasis and intestinal integrity under high-fat feeding conditions. Further immunological and molecular studies are recommended to elucidate the mechanism of action and optimal dosage.