The effect of orange peel on the oxidation stability of egg yolk

XU Feng;QIU Faming;QIU Yang;Baicheng Medical College;Jilin Stockbreeding School;Kunming Medical University Haiyuan College;

orange peel;;laying hens;;laying performance;;egg quality;;oxidation stability

The aim of the present study was to study the effects of dietary supplementation with orange peel on antioxidant capacity of egg yolk and the possible side effects on laying performance,egg quality of laying hens. A total of 378 animals,reared in 126 replicate enriched cages with 3 hens each,were randomly allocated into 3 treatment groups :control group that was offered a basal diet,treatment 1 group offered a diet supplemented with 9% orange peel and treatment 2 group that was offered the basal diet further supplemented with 0.8 g hesperidin and 0.005 g naringin per kg of feed. The diets were offered for 30 days and were isocaloric and isonitrogenous. Oxidative stability of egg,expressed as ng malondialdehyde(MDA)per g of yolk,performance and egg quality parameters were determined during experimental period. Oxidative stability of fresh and stored eggs for 30 and 90 d was improved when hens were fed a diet supplemented with orange peel in comparison with controls(P <0.05). Ten days of dietary supplementation with orange peel were enough for apparent beneficial effects on yolk oxidative stability and consequently egg shelf life. However,feed intake and laying rate were decreased whereas feed conversion ratio was increased in group of hens supplemented with orange peel in comparison with both controls and hens fed with hesperidin and naringin(P <0.05). The reduced values of feed intake may be attributed to the low palatability of orange peel and not only negatively affected performance but also resulted in deterioration of egg quality parameters. Hens fed with orange peel produced slightly lighter eggs with a lower eggshell percentage,thickness and strength and a less orange yolk color in comparison with controls(P <0.05). In summary,dietary supplementation with 9% orange peel significantly improved oxidative stability of both fresh and stored eggs in laying hens. However,the beneficial effect of orange peel on shelf life of eggs was accompanied by negative impacts on performance and egg quality. These adverse effects are attributed to the decreased feed intake,which resulted in insufficient nutrient supply that is necessary for adequate egg formation and production.