Effects of light-sources and photoperiod on hemato-physiological indices of broilers grown to heavy weights

Authors: Olanrewaju, Hammed; Collier, Stephanie; Purswell, Joseph - Jody; Branton, Scott

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2018
Publication Date: 2/15/2019
Citation: Olanrewaju, H.A., Collier, S.D., Purswell, J.L., Branton, S.L. 2019. Effects of light-sources and photoperiod on hemato-physiological indices of broilers grown to heavy weights. Poultry Science. 98(3):1075-1082.

Interpretive Summary: Most governments around the world including the USA have passed measures to phase out incandescent (ICD) bulbs due to its inefficiency in favor of more energy-efficient lighting alternatives, including cold cathode fluorescent lamps (CCFL), compact fluorescent lamps (CFL), and light emitting diodes (LED) among others. Although, most of the research involving light management has focused on light sources, photoperiods, or each in combination with other environmental factors, more studies are still necessary to examine the effects of light sources in combination with photoperiods to understand the adequate light program (light sources, photoperiod) that can maximize growth performances of modern broilers grown to heavy weights without any negative impact on poultry welfare. In each trial of the 4 trials, we evaluated the effects of light sources and photoperiod on blood physiological indices of broilers grown to heavy weights. The results indicated that light sources had effects on some of the selected blood physiological indices, while short/non-intermittent photoperiod had effects on most of the selected blood physiological indices. However, all these changes were still within the normal acid-base homeostasis and physiological ranges of this species. Plasma corticosterone and glucose 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 the regular/intermittent photoperiod. Commercial poultry facilities can thereby reduce energy costs and optimize production efficiency without compromising the welfare of broilers grown to heavy weights (> 3 kg).

Technical Abstract: We evaluated the influence of light sources and photoperiod on blood physiological variables in 4 trials. In each trial, 720 1 d old Ross × Ross 708 chicks were randomly distributed into 12 environmentally-controlled rooms (30 males/30 females/room). The experimental design was a 4 × 3 factorial treatments consisting of 4 light sources [incandescent (ICD, standard), compact fluorescent (CFL), neutral light emitting diode (Neutral-LED), and cool poultry-specific-filtered LED (Cool-PSF-LED)] and 3 photoperiods [long/continuous (23L:1D), regular/intermittent (2L:2D), and short/non-intermittent (8L:16D)] from d8-d56 at 50 % RH. Birds were fed the same diet, while feed and water were provided ad libitum. Blood samples were collected from the brachial wing vein on d 14, 28, 42 and 56 of age and analyzed immediately. Light sources had significant (P = 0.05) effects on BW, and some of the selected blood physiological indices except Hb, Hct, Ca2+ angap, glucose and corticosterone. Also, the photoperiods had significant (P = 0.05) effects on BW and most of the selected blood physiological indices except HCO3-, angap, glucose, corticosterone, and T4. However, all these changes were still within the normal acid-base homeostasis and physiological ranges of this species. Acid-base regulation during the short photoperiod exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH, due to a respiratory acidosis. Plasma corticosterone and glucose 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 the regular/intermittent photoperiod. Commercial poultry facilities can thereby reduce energy costs and optimize production efficiency without compromising the welfare of broilers grown to heavy weights (> 3 kg).