The Effect of Oxidized Fish Oils on Growth Performance, Oxidative Status, and Intestinal Barrier Function in Broiler Chickens

The objective of this study was to determine the effect of oxidized fish oils on growth performance, metabolic oxidative status, and intestinal barrier function in broiler chickens. A total of 240 1-d-old female broiler chickens were assigned to 4 dietary treatments. Dietary treatments comprised of a basal diet supplemented with 4% of non-oxidized (fresh) fish oil, low-oxidized fish oil (FLX), moderately oxidized fish oil (FMX), and highly oxidized fish oil (FHX). Serum corticosterone levels at day 14 and liver concentrations of malondialdehyde (MDA) at day 14 and 21 were higher in birds fed oxidized fish oil compared with those fed then non-oxidized fish oil diet (P < 0.01 in both cases). Furthermore, mRNA expression levels of claudin-1 and occludin were reduced, while those of IL-22 and catalase were increased, in the livers of birds fed the highly oxidized oils compared with those fed fresh fish oils (P ≤ 0.001 in all cases). These results indicate that supplementation of broiler diets with 4% oxidized fish oils can cause lipid peroxidation in the liver, involving increased concentrations of MDA, impaired gut barrier function as a result of increased intestinal permeability due to decreased expression of the tight junction proteins claudin-1/occludin, and intestinal inflammation mediated via upregulation of IL-22 expression in the mucosal tissues.