An Indication of Reliability of the Two-Level Approach of the AWIN Welfare Assessment Protocol for Horses.

To enhance feasibility, the Animal Welfare Indicators (AWIN) assessment protocol for horses consists of two levels: the first is a visual inspection of a sample of horses performed from a distance, the second a close-up inspection of all horses. The aim was to analyse whether information would be lost if only the first level were performed. In this study, 112 first and 112 second level assessments carried out on a subsequent day by one observer were compared by calculating the Spearman's Rank Correlation Coefficient (RS), Intraclass Correlation Coefficients (ICC), Smallest Detectable Changes (SDC) and Limits of Agreements (LoA). Most indicators demonstrated sufficient reliability between the two levels. Exceptions were the Horse Grimace Scale, the Avoidance Distance Test and the Voluntary Human Approach Test (e.g., Voluntary Human Approach Test: RS: 0.38, ICC: 0.38, SDC: 0.21, LoA: -0.25-0.17), which could, however, be also interpreted as a lack of test-retest reliability. Further disagreement was found for the indicator consistency of manure (RS: 0.31, ICC: 0.38, SDC: 0.36, LoA: -0.38-0.36). For these indicators, an adaptation of the first level would be beneficial. Overall, in this study, the division into two levels was reliable and might therewith have the potential to enhance feasibility in other welfare assessment schemes.