Effects of naturally oxidized n-3 oil sources on performance, egg quality, yolk fatty acid profile, serum biochemical parameters and liver histopathology in laying Japanese quail.

Although n-3-rich oils are widely used to improve the fatty acid profile of eggs, their susceptibility to oxidation may reduce their nutritional benefits and adversely affect animal health. However, the effects of naturally oxidized n-3 oil sources in laying Japanese quail remain unclear. This study therefore evaluated the effects of naturally oxidized plant and animal oil sources on productive performance, egg quality, egg yolk fatty acid profile, serum biochemical parameters, and liver histopathology. A total of 160 laying Japanese quail (Coturnix coturnix japonica) were assigned to four dietary treatments containing 1.5% non-oxidized sunflower oil, naturally oxidized chia oil, naturally oxidized flaxseed oil, or naturally oxidized salmon oil, designated as the Control, CO, FO, and SO groups, respectively. Each treatment consisted of five replicates of eight birds, and the experiment lasted 6 weeks. Egg production and feed conversion ratio were not affected by dietary treatment. However, feed intake decreased in the FO group, whereas egg weight decreased in the FO and SO groups (P < 0.05). Among the egg quality traits, yolk index increased in the CO group, while albumen index decreased in the FO group (P < 0.05); the remaining traits were unaffected. Egg yolk n-3 fatty acid content and the n-3/n-6 ratio increased significantly in the CO and FO groups (P < 0.01), whereas yolk cholesterol concentration and serum biochemical parameters did not differ among treatments. Liver histology was normal in the Control group, while the oxidized oil groups exhibited histopathological alterations, predominantly steatosis, with severity varying among oil sources. These findings indicate that naturally oxidized chia and flaxseed oils can enhance the n-3 fatty acid profile of egg yolk, but their potential effects on performance and liver health should be considered. Therefore, both oil source and oxidative status are important practical considerations when formulating n-3-enriched diets for laying Japanese quail.