www.nature.com/scientificreports OPEN received: 29 July 2016 accepted: 29 November 2016 Published: 23 December 2016 Melatonin implantation improved the egg-laying rate and quality in hens past their peak egg-laying age Yaxiong Jia1,*, Minghui Yang2,*, Kuanfeng Zhu2,*, Liang Wang1, Yukun Song2, Jing Wang2, Wenxiang Qin2, Zhiyuan Xu2,3, Yu Chen1 & Guoshi Liu2 The egg-laying rates of hens approximately 470 days of age exhibited a positive correlation to blood melatonin levels The hens with an egg-laying rate