Influence of Light Sources and Photoperiods on Blood Physiological variables Broilers grown to heavy weights

Abstract

There are a number of studies on the effect of different light sources especially ICD light on the physiology of broilers grown to 2.1 kg, but fewer such studies with conflicting reports are available on growth performance and blood physiological parameters of broilers grown to heavy weights (greater than 3 kg). We evaluated the influence of light sources and photoperiod on blood physiological parameters in 2 trials. A total of 720 1‐d‐old Ross × Ross 708 chicks were randomly distributed into 12 rooms (30 male and 30 female chicks/room). The 3 light sources consisted of compact fluorescent (CFL), light emitting diode (LED), and poultry specific filtered LED (PSF‐LED) and incandescent (ICD, standard) from d 1 to d 56 and 3 photoperiods (long/continuous [23L:1D] from d8–d56; regular/intermittent [2L:2D], and short/non‐intermittent [8L:16D] from d8–d48 and 23L:1D from d49–d56, respectively) at 50 % RH. Similar feed and water were provided ad libitum to all chickens. Arterial blood samples were collected on d 14, 28, 42, and 56 of age and analyzed immediately. Light sources, age, and sex had significant (P ≤ 0.05) effects on BW, Hb, Hct, electrolytes, angap, and mOsm, but all these changes were still within the normal acid‐base homeostasis and physiological ranges. Also, the short photoperiod significantly (P ≤ 0.05) reduced BW, pH level, pO2, sO2, and Ca2+, while significantly (P ≤ 0.05) elevating pCO2, Hct, Hb, and McHc concentrations. Acid‐base regulation during short photoperiod exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH, due to a respiratory acidosis. Plasma corticosterone concentrations were not affected by treatments, suggesting an absence of physiological stress. It was concluded that the 3 LED light bulbs evaluated could be suitable for replacement of ICD along with regular/intermittent photoperiod for commercial poultry facilities to reduce energy costs and optimize production efficiency without compromising the welfare of broilers grown to heavy weights.