The bird has two photoreceptors, one is the retina receptor, the eye, and the other is in the hypothalamus. Light stimulation reaches the hypothalamus through the optic nerve of the optic nerve; in addition, light can also act on the pineal and hypothalamus directly through the skull. When the hypothalamus receives stimulation, it secretes gonadotropin-releasing hormone. This hormone reaches the anterior pituitary through the pituitary portal system, causing the secretion of follicle stimulating hormone and ovulation hormones, and promoting follicular development and ovulation. Developed follicles produce estrogen, which promotes hens' fallopian tube development and secondary sexual manifestations. Ovulation hormones cause ovulation in hens.
Artificial light is often used to supplement natural light in the production of layered chickens, or only artificial light is used to properly regulate the light required by the layer. Appropriate lighting can increase the egg production of laying hens and speed up the broiler's weight gain, so that the chicks have enhanced blood circulation, increased appetite, calcium and phosphorus metabolism, and enhanced immunity.