Morphometric Characterization of Northeastern Donkeys from the Brazilian Semi-Arid Region: A First Step Toward Conservation

The Northeastern Donkey represents an important animal genetic resource adapted to the semi-arid conditions of Brazil, being recognized for its hardiness and ability to survive under challenging environmental conditions. However, the progressive reduction in the use of these animals in productive activities has contributed to population decline and increased concerns regarding the loss of genetic diversity. In this context, the present study aimed to characterize the morphometric variability of a Northeastern Donkey population from the Brazilian semi-arid region. A total of 51 adult donkeys were evaluated using linear and circumference measurements obtained with a measuring tape and a hippometer. Data were analyzed using principal component analysis (PCA), hierarchical and non-hierarchical cluster analyses (k-means), analysis of variance, and canonical discriminant analysis. A descriptive three-component PCA solution summarized body circumference and overall body size, limb robustness, and animal stature and linear body dimensions, explaining 74.49% of the total variance; however, parallel analysis supported only two components, so the three-axis interpretation remains exploratory. Cluster analysis identified three morphostructural profiles corresponding to small-, intermediate-, and large-sized animals. Classification consistency was subsequently assessed using canonical discriminant analysis, which achieved 98.0% apparent classification accuracy and 88.2% accuracy under leave-one-out cross-validation. The small and large profiles occurred exclusively in Santa Quitéria and Aquiraz, respectively, indicating potential facility-related influences. The results demonstrate phenotypic variability within the evaluated sample and contribute to a better understanding of the morphological diversity of the Northeastern Donkey. Furthermore, the identification of distinct morphostructural profiles provides valuable information for conservation initiatives, population characterization, and the sustainable management of this threatened local genetic resource.