摘要：Recent studies showed that apart from photostimulation, metabolic triggers may independently activate sexual maturation and egg pr

Recent studies showed that apart from photostimulation, metabolic triggers may independently activate sexual maturation and egg production in chickens. However, the origin, mode of action, and specific target(s) of this metabolic control remain unknown. Beyond body weight (BW), we hypothesize that body composition (BC) and associated specific metabolic signals are involved. Thus, this study was conducted to determine the BW and BC thresholds triggering spontaneous sexual maturation in layer pullets under different growth trajectories. Day-old Lohman LSL lite and Lohman brown lite chicks (n = 210 each) raised in brooding cages under ad libitum (AL) feeding until 8 weeks of age were randomly allocated into individual cages and assigned to one of 3 experimental growth profiles; AL, breeder’s target (T), restricted 20% below target (R), (n = 70 birds/profile/strain). Birds had free access to water throughout the trial. All hens were maintained on 10 h of light (10 lux) throughout the rest of the study. Blood and tissue samples were collected throughout the study to measure plasma estradiol (E2) concentrations and organ weights, respectively. Furthermore, carcasses were subjected to Dual-energy X-ray absorptiometry (DEXA) analyses. All analyses were completed with SAS using the MIXED procedure. Results show that R treatment slowed (p

Chickens are seasonal breeders, relying on changes in photoperiod to initiate and terminate reproduction. However, it has also been shown that apart from photostimulation, metabolic triggers can independently activate sexual maturation and egg production in both layers and broiler breeders。

Thus, it is evident that growth trajectories can influence the initiation of reproduction, possibly at all levels of the hypothalamic-pituitary-ovarian axis. However, the origin, mode of action, and specific target(s) of this metabolic control remain to be determined. Beyond body weight (BW), body composition (BC) may be directly related to metabolic input on sexual maturation in chickens. Studies in broiler breeders and quail revealed that specific BW and BC are required to initiate maturation。

来源：鸡保姆