Effects of environmental temperature and light intensity on blood physiological parameters of broilers

Abstract

This study examined the effects of atmospheric temperature, light intensity, and their interaction on blood acid‐base balance and electrolytes in broiler chickens under environmentally controlled conditions in 2 trials. The experiment consisted of a factorial arranged in a randomized complete block design with 9 treatments consisted of 3 levels (Low=15.6, Moderate=21.1, High=26.7 °C) of temperatures and 3 levels (0.5, 3.0, 20 lx) of light intensities from d 21 to 56 d of age at 50% RH. Five hundred and forty (30 male/30 female) Ross × Ross 708 chicks were randomly distributed into 9 chambers at 1 d of age. Feed and water were provided ad libitum. Venous blood samples were collected on d 21 (base line), 28, 42, and 56. High temperature significantly (P ≤ 0.05) reduced BW, partial pressure of CO2 (pCO2), bicarbonate, hematocrit, hemoglobin, Ca2+, K+, and Na+ while significantly (P ≤ 0.05) elevated pH level, glucose, osmolality, and anion gap concentrations. Partial pressure of O2 (pO2) was slightly increased when related to ambient temperature. There was no effect of light‐intensity on most of the examined variables. Acid‐base regulation during high ambient temperature and light intensity exposure had not deteriorated despite lower pCO2 that consequently increased blood pH, due to a compensatory decrease in HCO3− concentration. Plasma corticosterone was not affected by temperature, light intensity or their interaction. These results indicate that continuous exposure of broiler chickens to high temperature, high light intensity or their interaction markedly affects some physiological blood variables without inducing stress in broilers.