EFFECT OF MONOCHROMATIC GREEN LED LIGHT STIMULI DURING INCUBATION ON EMBRYO GROWTH, HATCHING PERFORMANCE, AND HORMONE LEVELS

Previous research indicated improvement of incubation by light stimuli. However, the light source arrangement, usually with irradiation from top to bottom, was inconvenient and high in cost. Among the different light colors, the effects of green LED light stimuli during embryo development were inconclusive. In this study, two LED lamps were installed on both sides of egg trays, and the irradiation was directed from the edges to the middle. The effect of green LED light with various light intensities was investigated. A total of 1408 broiler eggs were randomly allocated to high light (300 lx), middle light (150 lx), low light (50 lx), and dark treatments with four replicates. Embryo weight, body length, organ weight, hatching performance, and serum hormone levels were tested. The results indicated that incubation of the broiler eggs under an appropriate light intensity (low light treatment, 50 lx) of green light significantly increased embryo weight, body length, and hatchability (p < 0.001). According to the serum hormone tests, only the low light treatment significantly increased the thyroxine (T4) levels of the chicks (p < 0.05) at hatching, but the middle and high light treatments slightly decreased the T4 and testosterone (TES) levels of the chicks compared with the dark treatment. Moreover, peak hatching time occurred 12 h earlier in the light treatments compared with the dark treatment. In conclusion, an appropriate light intensity (low light treatment, 50 lx) of LED green light improved embryo growth and hatching performance, but excessive light intensity reduced the positive effects or even produced slight negative effects on the T4 and TES levels of chicks at hatching.