II. Evaluation of the impact of alternative light technology on male broiler chicken stress

Abstract

This study evaluates the impact of light-emitting diodes (LEDs), cold cathode fluorescent lamps (CCFLs), and incandescent lamps on broiler welfare in response to recent interest in the agriculture industry to transition to more energy-efficient lighting technologies. Male Ross 708 broilers (n = 672) were raised to 6 wk age in 8 light-tight modified large colony houses under identical intermittent lighting conditions using 4 unique types of lamps, which were gradually dimmed throughout the study. Incandescent lamps served as the control; experimental technologies tested were a CCFL, and 2 different LED lamps. Each technology was tested in duplicate for each of the 4 trials (8 replications total per technology) conducted across the course of one year to account for seasonal variance. Birds were removed from each house at days 7, 14, 35, and 42 to be humanely euthanized and weighed for necropsy evaluation and comparison of body mass. Blood collection via cardiac puncture was performed to obtain heterophil to lymphocyte (H:L) ratios for evaluation of environmental stress. Birds raised under CCFLs had significantly lower body weights (2,871 g ± 53) than the control (3,000 ± 33 g) by 42 d. Birds raised under CCFLs additionally had significantly higher H:L ratios (0.68 ± 0.06) than the control (0.53 ± 0.03), indicating that these birds may have been chronically stressed (P = 0.03). There were not significant differences in the H:L ratio between LED technologies at α = 0.05. A significant age and seasonal correlation in H:L ratios was observed across all technologies, along with significant differences among birds raised under the experimental technologies. This study indicates that variation in broiler body weight and stress may be attributed in part to lighting technologies implemented in broiler houses.