Abstract
Linear appraisal scales focus on the qualitative assessment of specific traits along a standardized scale across animal populations. By minimizing errors and optimizing measurement procedures, these scales streamline resource allocation, saving time and costs for livestock managers and breeders, thereby facilitating informed breeding decisions and promoting genetic progress. A total of 130 adult, healthy dromedary camels (Camelus dromedarius) of the Canarian Camel breed were evaluated across three representative locations in Spain (Huelva, Almería, and Fuerteventura). The study aimed to optimize and validate a linear appraisal system (LAS) for assessing zoometric traits in dromedaries. Principal Component Analysis (PCA) revealed that none of the zoometric variables considered were discardable due to their ability to explain variability in the sample. However, some zoometric variables lacked statistically significant representation across one or more levels within the linear appraisal scale. Therefore, a proposal for optimizing the linear appraisal scale involves reducing the number of initially proposed linear categories for these variables. Correlation analysis revealed high internal consistency (Intraclass Correlation Coefficient (ICC) ≥ 0.7), confirming significant agreement between zoometric variability-based scales and linear appraisal traits, thus validating the LAS. Notably, interobserver reliability varied across zoometric traits, with lower agreement (ICC < 0.5) observed in apical body regions, which are more prone to movement during evaluation. Overall, our findings underscore the potential of LAS as a robust tool for zoometric evaluation in dromedary camels, aiding in the selection of superior individuals for breeding. In this context, the LAS provides a valuable framework to improve phenotypic characterization of dromedary camels, a livestock species of growing global interest due to its resilience to climate change and its longstanding role as a socio-economic cornerstone in arid and semi-arid production systems. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11250-025-04628-9.