![]() ![]() However, little is known about the effect of OPN5 in non-seasonal breeding birds. OPN5 has been considered as candidate DBPs involving in regulation of seasonal reproduction in birds. Birds translates photoperiodic information into neuroendocrine signals through deep brain photoreceptors (DBPs). Photoperiod is an important environmental factor that influence seasonal reproduction behavior in bird. The results suggest that the inhibition of follicle development and reduced egg production in quail by short day treatment is due to GnIH acting at the gonadal level, and GnIH affected the steroid synthesis by inhibiting gonadotropin receptors. In vitro culture of quail granulosa cells and treatment with GnIH inhibited the levels of FSHR, LHR and steroid synthesis pathways in granulosa cells, upregulated the levels of AMH, AMHR2, GDF9 and BMP15. The result showed that short day treatment up-regulated the level of GnIH in the gonads (P<0.05), decreased the expression level of CYP19A1,3β-HSD, StAR, LHR and FSHR and increased the expression level of AMH, AMHR2,GDF9 and BMP15 to inhibit follicle development and ovulation, thus affecting the egg production performance of quails. Samples were collected from each group on d1, d11, d22 and d36 of the experiment. To investigate the expression of GnIH and its effects on follicle development and steroidogenesis in quail ovaries under different photoperiods, 72 healthy laying quails of 8-week-old were randomly divided into long day (LD) group (n = 36) and short day(SD) group (8L:16D) (n = 36). Photoperiod is an important environmental factor that influence seasonal reproduction behavior in bird and GnIH can play a function in this process through the reproductive axis, and some studies suggest that GnIH may have a direct role at the gonadal level. ![]() Extending photoperiods may improve the laying performance of ducks by reducing plasma levels of GnIH hormone and the expression of GnIHR and melatonin receptor genes. This study found that the average laying rate and the average egg weight of ducks in the LP group both increased. ![]() Altogether these results suggest that extended photoperiods may promote the laying performance of ducks by inhibiting the secretion of GnIH and the expression of GnIHR and melatonin receptor genes. The expression of Mel‐a in large white follicles, and Mel‐b and Mel‐c in the hypothalamus were also downregulated in the LP group. GnIHR gene expression in the pituitary and large yellow follicles were downregulated in the LP group. Compared to the SP group, GnIH plasma concentration was decreased in the LP group, whilst FSH was increased in the LP group. The results showed that laying performance was greatest in the LP group including laying rate, average egg weight and feed‐egg ratio. Laying performance, endocrine‐related hormones and gene expression of three groups were compared. ![]() To reveal the effects of light on the laying performance of ducks and its possible regulatory mechanisms, Shanma ducks at 52 weeks age were divided into three group treated with different photoperiods of 16 hr (control group), 24 hr (long‐photoperiod group, LP), and 8 hr (short‐photoperiod group, SP). Light mainly affects animal reproductive performance through the hypothalamus‐ pituitary‐gonadal axis, but the specific regulating mechanism is not yet clear in duck. ![]()
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