5. Conclusion
The effects of different dietary levels of peppermint leaves on productive performance, egg quality and serum biochemistry showed that 12 weeks administration of these leaves have beneficial effects on egg production, egg weight, egg mass, feed intake, FCR, HU, eggshell and serum cholesterol during the late laying period in Hy-Line brown hens. More detailed studies are needed in future to determine the optimal dietary inclusion level and its economic impact.