The Effect of colour temperature of light on egg production parameters and gene expression pattern of Heat Shock Protein 27 in layers

Objective: To evaluate the effects of different light colour temperatures on egg production parameters and heat shock protein gene expression (HSP 27) in Fayoumi chicken layers. Animals: 165 Fayoumi healthy pullets (17 weeks). Design: Randomized-controlled experimental study. Procedures: The birds were exposed to natural day light with photoperiod 12L: 12D, from 19th week, lighting schedule was gradually increased half an hour every week till it reached 16L:8D lighting schedule at laying at 24 weeks of age. At laying, the birds were allocated into three groups at a density of 9 birds/m2. The first group (control 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). The third group was exposed to warm white LED light (yellow light) (2700 kelvin) till the end of the experiment. Eggs were collected daily; egg number, weight and mass were recorded for each group. Liver samples were collected for RNA extraction. Results: The results showed that egg number, egg weight and egg mass were significantly increased in blue light group (P ≤ 0.05) and HSP 27 gene expression was significantly upregulated (P ≤ 0.05) in this group of chicken in comparison to the control group. Conclusion and clinical relevance: It is concluded that the blue LED light may be suitable for use in layer farms to optimize reproductive efficiency of birds.