Interactive effects of light-sources, photoperiod, and strain on blood physiological variables of broilers grown to heavy weights

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

Submitted to: International Journal of Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/2019
Publication Date: 1/15/2020
Citation: Olanrewaju, H.A., Purswell, J.L., Collier, S.D., Branton, S.L. 2020. Interactive effects of light-sources, photoperiod, and strain on blood physiological variables of broilers grown to heavy weights. International Journal of Poultry Science. 19(2):86-96. 10.3923/ijps.2020.86.96.

Interpretive Summary: Most governments around the world including the USA have phased out incandescent (ICD) bulbs due to its inefficiency in favor of more energy-efficient lighting alternatives, including 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 factors. The rate of development differs among strains and lighting program needs may be strain specific for the two strains (A and B) used in this study in order to optimize growth performance. Substantial unbiased scientific information is limited on comparison of these two strains that are early- and late-developing broilers on the effect of differing photoperiods in combination with the new LED light-sources currently used by the poultry industry on blood physiological indices since establishing proper welfare practices are central to international trade negotiations of meat products. Therefore, the objective of this study was to evaluate the effects of light sources (CFL, LED, PS-LED) bulbs in comparison with incandescent (ICD) bulbs in combination with photoperiod on blood physiological indices that relates to welfare of these two broiler strains (A and B) grown to heavy weights (> 3.0 kg). In each trial of the 2 trials, we evaluated the effects of light sources, photoperiods, and strains on blood physiological variables of broilers grown to heavy weights. The results indicated that the specific main effects of light sources in combination with photoperiods on selected blood physiological variables were observed on these two major broiler strains grown to heavy weights, but all these acid-base changes are still within the normal acid-base homeostasis and physiological ranges. Plasma corticosterone and blood glucose concentrations were not affected by treatments, indicating an absence of physiological stress. It was concluded that the 3 light source bulbs evaluated in this study along with a regular/intermittent photoperiod in commercial poultry facilities would reduce energy costs and optimize production efficiency without compromising the welfare of broilers grown to heavy weights irrespective of strains. Furthermore, the results of this study supplement current knowledge of the blood gases, electrolytes, and metabolites of early- and late-developing broiler strains grown to heavy weights under environmentally controlled conditions.

Technical Abstract: Effects of light sources, photoperiods, and strains on blood physiological variables of broilers grown to heavy weights (> 3 Kg) were investigated in 2 trials. The experimental design was a 4 × 2 × 2 factorial consisting of 4 light sources [incandescent (ICD, standard), compact fluorescent (CFL), neutral LED (Neutral-LED), and cool poultry specific LED (Cool-PS-LED)], 2 photoperiods (Regular/intermittent [2L:2D], and Short [8L:16D], and 2 strains (A, B). In each trial, 480 (240 males/240 females) 1-d-old chicks of each strain from different commercial hatcheries were equally and randomly distributed into 16 environmental-control rooms (30 males + 30 females/room) at 50% RH. Each room was randomly assigned one of 16 treatments from d 1 to 56 d of age. Birds were provided similar diets. Feed and water were provided ad libitum. Venous blood samples were collected on d 14, 28, 42, and 56 of age and analyzed immediately. Light sources had significant (P < 0.05) effects on BW, electrolytes, pCO2, angap, T3, and T4 in comparison with birds reared under ICD. Short photoperiod significantly (P < 0.05) reduced BW, pH, pO2, SaO2, electrolytes, Osmo, and T3, along with significantly (P < 0.05) increased pCO2, Hb, Hct, and McHc compared with regular intermittent photoperiod. Acid-base regulation during the short photoperiod exposure had not deteriorated despite higher pCO2 that consequently decreased blood pH due to a respiratory acidosis. Also, Strain B had significantly (P < 0.05) increased BW, pCO2, HCO3-, McHc, electrolytes, angap, Osmo, and T3, along with significantly (P < 0.05) reduced pH level, pO2, SaO2, Hb, Hct, and T4 in comparison with Strain A. All these changes were within broilers normal acid-base homeostasis ranges. Plasma corticosterone and blood glucose concentrations were not affected by treatments, indicating an absence of physiological stress. It was concluded that the 3 light sources evaluated along with a regular/intermittent photoperiod in commercial poultry facilities would reduce energy costs and optimize production without compromising the welfare of broilers grown to heavy weights.