Abstract: 【Objective】The concentration of LH and FSH in peripheral blood was studied by monochromatic light and to provide a scientific data about the mechanism action of monochromatic light effect on productive performance in laying hens. 【Method】Nineteen to 53 weeks old Laying hens were exposed to red, green and blue light from light emitting diode (LED) lamps and incandescent light in this study. All light sources were equalized under 15 lx light intensity for 16 h daily. 【Results】The results show: 1) The rise length of LH and FSH in blue light was longest and the peak value of LH and FSH in blue light was appeared at the last time from 25-34 wk. The LH in white light was highest and significantly higher than those in other light groups from 37-49 wk and the rise of LH in red light was persistent from 40-49 wk. 2) Within 24h, there is only one peak of LH and FSH concentration in W, B and R light treatments respectively, the peak value of LH concentration in W, B and R light treatments were reached at 10h, 07h and 10h. The peak values of FSH concentration in W, B and R light treatments were reached at 13h, 07h and 10h respectively. 3) There are three peak value of LH and FSH concentration in G light treatment, both peak values of which were simultaneously reached at 07h, 16h, and 01h respectively. 【Conclusion】The secreting of LH and FSH was enhanced by blue light from 19-36 wk and the secreting of LH and FSH was enhanced by white and red lights from 37-53 wk. The peak values of LH and FSH in All lights were appeared at morning within 24h (except FSH in white light).

Key words: Monochromatic Light, LH, FSH, laying hens