Effect of Monochromatic and Combined Light Colour on Performance, Blood Parameters, Ovarian Morphology and Reproductive Hormones in Laying Hens

We evaluated the effect of monochromatic and combined light emitting diode (LED) light colour on performance, ovarian morphology, and reproductive hormone and biochemical blood parameters in laying hens. A total of 600 Hy-line Brown pullets, 12 weeks of age, were divided (25×4×6 = birds × replications × treatments) as follows: red (R), green (G), blue (B), and combinations of R → G and R → G → B treatments. Fluorescent white light (W) was the control. The results showed that higher egg production was found under the monochromatic R and combination R → G treatments, and that heavier eggs were laid by the B and G treatments (P<0.05). Consequently, better feed conversion ratio was attained in the R → G treatment. Serum follicle stimulating hormone and 17 -estradiol levels were significantly higher in the R and R → G treatments. B treated birds came into production 15 days later than those treated with R light. Organ weight (ovary and stroma) and ovarian follicle numbers (1-3 and 4-6 mm) were significantly higher in R treated birds, as well as serum glucose and triglyceride contents. Serum IgG concentrations and the heterophil to lymphocyte ratio were not influenced by light colour. In these laying hens, 14 h R with 2 h G light in the later part of the day increased reproductive hormone levels, ovarian weight, and follicle number and hence increased egg production. Thus, these results suggest that a combination of R → G light may be comparable with monochromatic R light to enhance egg production in laying hens.