Assessing broiler chicken welfare at the slaughterhouse

Abstract

The commercial broiler chicken industry in the United States produces billions of pounds of chicken meat each year. With an increasing number of broilers slaughtered for consumption, more broilers are at risk of welfare issues occurring during the preslaughter and slaughter process. Animal-based, resource-based, and management-based measures can be used to assess animal welfare, enable benchmarking, and guide future management decisions that can improve animal welfare outcomes. However, little is known about the prevalence of welfare issues during these processes, and their associated risk factors in the United States are unclear. Therefore, the objective was to improve understanding of how on-farm, preslaughter, and slaughter conditions impact welfare outcomes in broilers chickens recorded at the processing plant. Chapter 2 reviews to-date literature on preslaughter mortality, injuries, and their associated risk factors. In chapter 3, animal-based measures assessed at three commercial slaughterhouses were associated with transport-specific flock characteristics. This relationship varied depending on the slaughterhouse where broilers were processed. Older and younger broilers were more at risk to obtain a leg bruise or die during the preslaughter phase. Broilers housed at a higher stocking density on-farm were more likely to obtain a wing fracture and leg bruise during the preslaughter phase. Multiple welfare outcomes were associated with first-week mortality and total on-farm mortality. This indicates that flock health and quality are connected to welfare issues that occur prior to and during slaughter, although the relationships were sometimes opposing. In chapter 4, a novel animal-based measure of long-term distress, feather corticosterone concentration, was evaluated pre- and post-scalding at a slaughterhouse. Mean feather corticosterone concentrations were lower post-scalding compared to pre-scalding, indicating that the scalding process does impact these feather corticosterone concentrations, likely due to structural feather damage from agitation during the process. This indicates that feather samples should be collected prior to scalding for a biological interpretation of long-term distress or after scalding for a relative benchmarking of a retrospective welfare indicator across flocks. In conclusion, flock characteristics and slaughterhouse conditions can impact welfare outcomes during the broilers' last day of life. Likely because management of the flock, and subsequent health or quality of the flock, will impact the birds' resilience during this stressful phase. Understanding these relationships can improve management strategies for future flocks, potentially improve welfare outcomes and benchmark across other slaughterhouses in the United States.