Very cool white LED light improves reproductive performance and up-regulates expression of reproductive genes in layers

This study was carried out to evaluate the effect of light color temperature on reproductive performance and the expression pattern of GnRH-1 and FSH β genes in layers. At lay, 165 Fayoumi healthy pullets were separated into well ventilated, environmentally controlled rooms. Birds were allocated into three groups with 55 birds each (5 males and 50 females) till 3 months after laying, representing base generation (F0). Fertile eggs were collected and incubated, and the newly hatched chicks were also divided into three groups from the first day of life till 3 months after laying, representing the first generation (F1). In the two generations, the first group was exposed to cool white LED light (day light) (6500 kelvin); the second group was exposed to very cool white LED light (sky blue light) (10000 kelvin); and the third group was exposed to warm white LED light (yellow light) (2700 kelvin). The expression profiles of GnRH-1 and FSH β genes and the serum level of FSH were evaluated in birds of the two generations. Blue light-exposed groups exhibited better reproductive performance, higher up-regulation of GnRH-1 and FSH β genes and increased FSH levels than those exposed to either the white or yellow light colors. A comparison between F0 and F1 revealed an improved profile for F1 birds. It therefore appears that blue LED light could improve the reproductive status of laying chickens.