Flock Uniformity – A New Poultry Welfare Indicator?

Directive 2007/43/CE establishes the system for assessing the welfare of poultry at the slaughterhouse level, which consists of a systematic assessment of indicators by the slaughterhouse's official veterinarian (OV). In Portugal those indicators include mortality rate on the farm and during transport to the slaughterhouse, as well as post mortem findings such as footpad dermatitis (FPD). Nevertheless, the increasing importance of this topic leads to a dynamic search for novel welfare indicators such as flock uniformity. Reduced animal welfare can be indicated by poor flock uniformity due to either general housing or management problems, or bird health problems. For that reason, the aim of this study was to investigate the usefulness of the parameter “flock uniformity “(FU) as an indicator of animal welfare to be used during slaughter of commercial broiler flocks. For that, a total of 26 randomly selected mixed-sex Ross 308 broiler flocks were studied. All batches were raised under similar farm management systems with a medium age of slaughter of 35 days. To study the uniformity, 10% of each batch was observed and categorized after stunning at the slaughterhouse, using the following scores based on % of small animals observed: score 1 ([0 -2,5%[; high uniformity); score 2 ([2,5-5%[; normal uniformity); score 3 ([5-7,5%[; bad uniformity); score 4 (≥7,5%; no uniformity). Additionally, the following percentage data were collected for each flock: mortality in transport, total condemnation (TC), the % of TC only due to disease cause and the % of TC due to errors related to slaughter process. The results showed that poorer uniformity was highly associated with increased rejection level (p= 0.002) and increased rejections caused by disease (p = 0.001). This highlights the potential use of this parameter as an animal welfare indicator and also as a criterion to be used under a risk-based meat inspection approach: The worse the FU, the more time the OV must dedicate to the post-mortem inspection of that batch.