Validity and reliability of the Organic method used for assessment of plumage damage in laying hens.

Severe feather pecking is a persistent welfare concern in laying hens, leading to feather loss and potential pain and injury within commercial flocks. Evaluating the extent of plumage damage provides a practical measure of the prevalence and severity of this behavior. In Denmark, the Organic method was developed as a standardized tool for assessing plumage condition during on-farm welfare inspections. The present study aimed to determine the validity and reliability of the Organic method and to identify potential refinements to improve its accuracy. The Organic method was compared with four established assessment approaches: the Bilčík, Bright, Tauson, and Welfare Quality® (WQ) methods. The Organic and Bright methods are non-intrusive, i.e., the hens are observed from a distance, whereas the other methods require handling of the hens. Laying hens from organic commercial farms were transported to the experimental facility at AU-Viborg. Five groups of 150 hens, aged 25, 38, 50, 61, and 73 weeks, were assessed by five observers, with the Organic method applied twice per hen. The study found the Organic method to be easy to implement, even for observers with no prior experience. A sample size of 100 hens was sufficient to provide a reliable estimate of flock-level feather pecking. Based on the results, clarification of the threshold between scores 1 and 2 to "5 cm at the largest extent" is recommended. Overall, the Organic method offers a valid and reliable approach for assessing plumage condition and supports practical welfare evaluation in laying hens.