title: Melatonin implantation improved the egg-laying rate and quality in hens past their peak egg-laying age.
abstract: 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 <30%, 30~90% and ≥90% had blood melatonin levels of 5.8 ± 2.6, 74.0 ± 32.9 and 445.9 ± 115.3 ng/ml, respectively. When 10 mg of melatonin was implanted into the hens at 300, 360, 470 and 550 days of age, the egg-laying rates increased 4.63 ± 0.46%, 8.38 ± 1.45%, 4.93 ± 0.85% and 7.93 ± 0.91%, respectively, compared to that of the controls. Melatonin implantation in hens at 300-470 days of age was observed to enhance egg production and reduce the rate of appearance of sharpei eggs. Melatonin (10 mg) implanted in hens 360 days of age did not influence the blood levels of progesterone (P4) or the gene expression levels of ovarian follicle stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), oestradiol receptor alpha (ERα), superoxide dismutase 2 (SOD2) or melatonin receptor 1 (MT1). In contrast, melatonin significantly elevated the serum oestradiol-17β (E2) content, down-regulated the gene expression of gonadotropin-inhibitory hormone receptor (GnIHR), and enhanced the expression of melatonin receptor 2 (MT2). This result indicates that the improved egg-laying rate by melatonin was the result of increased serum oestradiol and decreased ovarian GnIHR. These alterations may be mediated by MT2 activation.
authors.affiliation: Beijing Animal Husbandry Station, Beijing, China.
authors.forename: Yaxiong
authors.initials: Y
authors.lastname: Jia
authors.affiliation: National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, China.
authors.forename: Minghui
authors.initials: M
authors.lastname: Yang
authors.affiliation: National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, China.
authors.forename: Kuanfeng
authors.initials: K
authors.lastname: Zhu
authors.affiliation: Beijing Animal Husbandry Station, Beijing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.affiliation: National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, China.
authors.forename: Yukun
authors.initials: Y
authors.lastname: Song
authors.affiliation: National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, China.
authors.forename: Wenxiang
authors.initials: W
authors.lastname: Qin
authors.affiliation: National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, China.|College of Animal Science and Technology, Jilin Agricultural University, Changchun, Jilin, China.
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Beijing Animal Husbandry Station, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.affiliation: National Engineering Laboratory for Animal Breeding, Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing, China.
authors.forename: Guoshi
authors.initials: G
authors.lastname: Liu
mesh_terms: D000375:Aging / Q000097:blood*; D000818:Animals; D030161:Avian Proteins / Q000096:biosynthesis*; D002645:Chickens / Q000097:blood*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D008550:Melatonin / Q000494:pharmacology*; D010063:Ovum
chemical_list: D030161:Avian Proteins; D008550:Melatonin