Light-mediated regulation of ovarian activity and ovi-position dynamics in layers

Light is a vital environmental regulator influencing the reproductive physiology, behaviour, and productivity of laying hens through its effect on the hypothalamic–pituitary–gonadal (HPG) axis. Photoperiod, light intensity, and wavelength determine the timing of sexual maturity, egg production rate, and egg quality. Light perceived by retinal and extra-retinal photoreceptors stimulates the secretion of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH), which coordinate ovarian development and ovulation. Controlled lighting during the rearing phase, particularly gradual photoperiod reduction, delays sexual maturity, enhances early-lay productivity, and increases initial egg size. During production, maintaining a consistent 16-hour light schedule with a minimum intensity of 1 foot-candle supports peak egg output. Red-spectrum light (620–700 nm) is especially effective in stimulating reproductive activity. Proper light installation, bulb spacing, and regular maintenance ensure uniform illumination, while housing type—dark-out, brown-out, or open—dictates the degree of light control required. Supplemental practices such as midnight feeding can boost feed intake during heat stress without disturbing circadian rhythms. Overall, strategic light management integrating photoperiod, intensity, and spectrum serves as a cost-effective, welfare-friendly approach to enhance reproductive efficiency, egg quality, and productivity in modern layer production systems.