Effects of far infrared ray illumination on the performance, blood biochemistry, and faecal microflora of laying hens at different production stages

This study investigated the effect of far-infrared ray (FIR) illumination on performance, blood biochemistry, and faecal microflora of laying hens at different production stages. A total of 360 Hy-line brown laying hens were randomly allocated in a 2 × 2 factorial arrangement with six replicates. Hens were distributed in two production stages (30–39 and 45–54 weeks-old). Each group was exposed to two light types (light emitting diode; LED and LED+FIR) in separate rooms. The LED treatment illuminated a wavelength of 650 ± 10 nm (0.65 ± 0.01 μm), while LED+FIR treatment emitted 15 ± 10 μm with an LED wavelength. The results showed an interaction between egg production stages and light types on the serum triglyceride concentration. The hens exposed to the LED+FIR and LED treatments showed similar egg production, feed intake, egg weight, feed conversion ratio (FCR), as well as albumen height, haugh unit, and shell thickness of eggs. LED+FIR substantially decreased the concentration of serum cholesterol (CHOL), HDL cholesterol (HDLC), and triglyceride (TG) compared to LED lighting. LED+FIR substantially reduced the number of total microbes, Escherichia coli, and Salmonella in faeces compared to birds exposed to LED light. These findings suggest that LED+FIR lights may improve hen health and the hen house environment.