Effects of color temperatures (Kelvin) of LED bulbs on blood physiological variables of broilers grown to heavy weights

Light-emitting diode (LED) lighting is being used in the poultry industry to reduce energy usage in broiler production facilities. However, limited data are available comparing efficacy of different spectral distribution of LED bulbs on blood physiological variables of broilers grown to heavy weights (>3 kg). The present study evaluated the effects of color temperature (Kelvin) of LED bulbs on blood physiological variables of heavy broilers in 2 trials with 4 replicates/trial. The study was a randomized complete block design. Four light treatments consisted of 3 LED light bulbs [2,700 K, (Warm-LED); 5,000 K, (Cool-LED-#1); 5,000 K, (Cool-LED-#2)] and incandescent light (ICD, standard) from 1 to 56 d age. A total of 960 1-day-old Ross × Ross 708 chicks (30 males/room 30 females/room) were equally and randomly distributed among 16 environmentally controlled rooms at 50% RH. Each of the 4 treatments was represented by 4 rooms. Feed and water were provided ad libitum. All treatment groups were provided the same diet. Venous blood samples were collected on d 21, 28, 42, and 56 for immediate analysis of selected physiological variables and plasma collection. In comparison with ICD, Cool-LED-#1 had greater (P < 0.05) effects on pH, partial pressure of CO₂ (pCO₂), partial pressure of O₂ (pO₂), saturated O₂ (sO₂), and K⁺. However, all these acid–base changes remained within the normal venous acid–base homeostasis and physiological ranges. In addition, no effect of treatments was observed on HCO₃⁻, hematocrit (Hct), hemoglobin (Hb), Na⁺, Ca²⁺, Cl⁻, mean corpuscular hemoglobin concentration (McHc), osmolality, and anion gap. Moreover, blood glucose concentrations were not affected by treatments. This study shows that the 3 LED light bulbs evaluated in this study may be suitable for replacement of ICD light sources in commercial poultry facilities to reduce energy cost and optimize production efficiency without inducing physiological stress on broilers grown to heavy weights.