Animal-based methods for the assessment of broiler chicken welfare in organic and conventional production systems

Abstract

Animal welfare is one of the pillars in organic broiler production, evident in practices such as utilizing slower-growing hybrids and maintaining lower stocking densities for the birds. However, despite these efforts, skepticism and uncertainty remain regarding the extent to which animal welfare objectives are achieved in organic farming. The primary aim of this study was to compare animal-based measures assessing positive and negative welfare between organic and conventional broiler chickens in Denmark. The selected positive welfare indicators included Qualitative Behavior Assessment (QBA) and observations of play behavior in an open-space test. An additional aim of this study was to examine the reliability of the method by having all QBA observations done by two observers. Negative welfare indicators included walking ability assessed using the 6-point Bristol gait score method and fearfulness assessed using a novel object test. Welfare assessments were conducted on-farm before slaughter at 31–33 days of age for conventional birds and at 49–55 days of age for organic birds. The results from the QBA indicated differences between organic and conventional production systems (P = 0.001). Specifically, organic broilers exhibited higher levels of active, energetic, positively occupied, happy, and agitated behaviors. Notably, the outcome of the QBA was influenced by the observer (P = 0.001); on average, one observer tended to assign higher scores specifically for depressed and distressed behaviors, while the other observer allocated higher scores to the remaining behavioral terms. Moreover, organic broilers tended to show better walking abilities than conventional broilers (P = 0.064). Fear responses were similar across both production systems. Finally, organic broilers demonstrated a lower frequency of play behavior in open spaces compared to conventional broilers (P = 0.001). Conventional birds may have expressed more play behavior due to the greater contrast between the sudden availability of open space and their typical stocking density, resulting in increased compensatory play. This presents a challenge since a higher frequency of play is often considered an indicator of positive welfare, but we speculate whether in this study, it might suggest a restriction of spontaneous play due to space limitations caused by the high stocking density in the conventional production system. As a result, when additional space becomes available, it could lead to a rebound effect. Future research should explore how stocking density influences play behavior in broiler chickens, including measures of both spontaneous play and stimulated play during controlled test situations.