光信号调控鸡胚生物钟昼夜节律系统缩短出雏窗口期的机制研究

Hatch window is a key factor modulating the healthy hatching rate of poultry. As the principal environmental factor, light contributes to the synchronization of the circadian clock with the external environment. Therefore, light controlling may be a potential solution to shorten hatch window under modern incubation conditions. Our previous studies suggested that the monochrome LED green light could promote the growth and development of chick embryos and shorten the incubation time. However, due to the limited light rhythm, more studies should be presented to target the problem of shortening hatch window and improving the consistency of hatching. Herein, LED monochrome green light was employed as the light source in this study to explore the effect of different light rhythm and initial light signal on the circadian clock system of hypothalamus and pineal of chick embryos. In addition, video monitoring and machine vision technology were combined to analyze the number and effect of the hatched chicks. The mechanism of the light signal controlling the circadian clock system of chick embryos to shorten the hatch window was exploited. This project is conducive to enriching the theoretical basis of shortening the hatch window by light signal controlling. It is also involved in promoting the scale and refined development of China's poultry incubation industry and the collaborative innovation with the livestock and poultry LED lighting industry.

出雏窗口期是影响家禽孵化健雏率的关键因素，家禽对光高度敏感，光是影响生物钟与外界环境同步的首要环境因素，现代孵化条件下，可将光调控作为缩短出雏窗口期的新途径。本项目前期预研发现LED单色绿光可促进鸡胚生长发育，缩短整体孵化时间，但预研中光节律单一，并未解决缩短出雏窗口期、提高出雏一致性的问题。基于文献推测LED单色绿光可作为光信号调控鸡胚生物钟昼夜节律缩短出雏窗口期。本项目拟采用LED单色绿光为光源，探究不同光节律及初始光信号调控对鸡胚下丘脑和松果体生物钟昼夜节律系统的影响，并在出雏窗口期采用视频监测结合机器视觉技术对雏鸡出雏时间及效果进行统计分析，进行光信号调控鸡胚生物钟昼夜节律系统缩短出雏窗口期的机制研究。本项目的实施有助于丰富光信号调控孵化节律缩短出雏窗口期的理论基础，有利于推动我国家禽孵化产业规模化与精细化发展及其与畜禽LED照明产业的协同创新。

本研究探讨了不同光照节律单色绿光处理对孵化期间的胚胎发育、呼吸速率以及孵化窗口期的影响，并搭建鸡胚心率检测平台对孵化期间的鸡胚进行不同光环境参数的刺激获取鸡胚不同阶段光环境参数的科学响应值，进行光环境参数及光照模式的优化，得出可改善出雏窗口期的优选光照方案，并结合天然化合物抗应激活性探究在孵化期间胚内给养降低鸡胚光照应激性的可能性。研究结果表明低光照强度（50lx）下，单色绿光处理虽可促进胚胎发育，提升代谢速率的增强促进雏鸡提早出雏，但出雏窗口期并未得到明显改善；单色绿光环境下，在鸡胚发育的中前期（9day）仅需50lx即可产生显著性的响应，在鸡胚发育的后期（15day）需要150lx及以上强度才发生显著性的心率升高响应；相对于黑暗孵化处理，光照节律为12L:12D、强度150lx-300lx持续性光照模式的单色绿光处理可以将出雏窗口期缩短约9h（窗口期全长21h），大幅度提高出雏效率。光照处理组在非光照期间（第6h，夜间）和光照期间（第18h，昼间）对鸡胚下丘脑和肝脏的钟基因表达具有显著影响，相对于黑暗孵化处理，光照孵化处理具有更加明显的昼夜节律表达差异，间歇式光照模式虽可优化出雏窗口期，但效果不及持续性光照模式，且造成前期死胚率较高。单色绿光处理在孵化期间虽然可调控鸡胚的生长节律，但也会导致应激影响鸡胚生长发育；天然活性物质的摄入可有效提升家鸡生长早期健康状况、抗氧化能力、免疫反应，促进养殖健康发长，为胚内给养联合单色绿光进行出雏窗口期调控的探索研究提供了理论基础。本研究的开展有助于为单色绿光调控孵化技术走向畜禽养殖精细化产业应用提供新的方法和思路。