Impact of dietary quercetin on laying hen performance, egg quality and yolk oxidative stability

The objective of the present study was to investigate the effect of the natural flavonoid quercetin dietary supplementation on laying hens' performance, egg quality parameters and yolk oxidative stability. One hundred and ninety two laying hens were allocated into 4 treatment groups: the control (C) group that was fed with a commercial basal diet and the other experimental groups that were offered the same diet further supplemented with quercetin at 200, 400 and 800 mg per kg of feed (Q2, Q4 and Q8 group, respectively) for 28 days. Supplementation with quercetin at 400 mg per kg of feed increased feed intake and eggshell weight in comparison with the groups fed with 200 and 800 mg per kg of feed (P < 0.05) but no significant differences were found compared to the controls (P > 0.05). Egg yolk cholesterol levels were increased with increased levels of quercetin in hens diet (P, P-linear < 0.05) whereas blood serum cholesterol levels remained unaffected by quercetin treatment (P, P-linear > 0.05). Egg yolk oxidative stability was improved even from the 4th day of supplementation with quercetin (P, P-linear < 0.05). This beneficial effect was also observed in eggs that were stored for up to 90 d (P, P-linear < 0.05). In conclusion, quercetin may favorably prolong shelf-life of eggs, without any side effects on hen performance and egg quality traits.