As an important indicator of sexual maturity of hens, age at first egg (AFE) is significantly associated with reproduction performance. In this study, 400 hens were divided into 6 groups based on AFE to analyze the difference of reproduction performance, reproduction hormone levels and the characterization of the hypothalamo-pituitary-gonadal axis in chickens. The results showed that the egg production of the hens in the late-maturing groups was significantly lower than that of the ones in other groups and the precocious hens had a lower egg production rate. The hens in late-maturing group had a lower fertility rate, LH levels and shorter duration of peak of egg production (PEP), the precocious hens had lower PRL levels. In addition, the characterization of the hypothalamo-pituitary-gonadal axis showed that the individuals with normal AFE had higher GNRH, GNRHR, ESR1, KITLG, and CYP11A1 expression levels than late-maturing and precocious individuals, which indicated that the chickens with normal AFE advantages on reproduction regulation system.
Keywords: age at first egg; hens; mRNA expression; reproductive traits; sexual maturity.
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