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.
Highlights
MethodsThe melatonin implants were made by the Specialty Institute, Chinese Academy of Agricultural Sciences
Peak or earlier in chickens[3,11,16,21,22]
Higher blood melatonin levels in hens 470 days of age were associated with more egg production
Summary
The melatonin implants were made by the Specialty Institute, Chinese Academy of Agricultural Sciences. We selected 120 hens (Beijing Red No 1) 300 days old, divided them into four groups, and treated them with either 0, 5, 10 or 20 mg of melatonin implants (C, 5 mg, 10 mg, and 20 mg groups, respectively). We randomly divided 240 hens (120 hens 360 days of age and 120 hens 470 days of age) into four groups at each age and treated them with 0, 10, 20 and 30 mg of melatonin (C, 10 mg, 20 mg, and 30 mg groups, respectively). We divided 60 hens 550 days old into 4 groups, and their treatment was the same as the hens in the 300-day-old groups. Hens of different ages came from different hatches
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
