Animal-Based Indicators for Assessing Welfare Implications Related to Growth Rate in Broilers

Rapid growth in broiler chickens is linked to significant welfare concerns. This guidance identifies animal-based indicators (ABIs) most suitable for assessing growth rate–related welfare. Walking ability is the most robust indicator, with strong evidence that faster growth impairs gait and is associated with pain, health issues, and reduced behavioural expression. Indicators of prolonged litter contact (e.g., footpad dermatitis, cleanliness) add context but depend on environmental conditions. Leg straightness reflects structural effects of growth, while activity measures (e.g., standing vs. immobile) complement mobility assessment. Other ABIs (e.g., mortality, behaviour, integument) provide broader context but are less specific to growth rate. Fear-based tests are unreliable. Overall, mobility- and activity-related ABIs should be prioritised, supported by standardised, multi-indicator assessments.