ETUDE BIOMETRIQUE DE LA POPULATION CAMELINE « SAHRAOUI » DANS LE SAHARA SEPTENTRIONAL ALGERIEN

Abstract

L‘objectif de cette étude était de fournir un profil morphométrique et d'estimer les indices corporels et le poids vif du dromadaire afin de fournir une base de connaissances pour une meilleure identification de la race. Treize mensurations corporelles ont été effectuées sur un échantillon de 150 dromadaires (27 mâles et 123 femelles) adultes. Les mesures corporelles ont été prises à l'aide d‘une toise de 2,5 m et d‘un mètre ruban rétractable de 5 m. Le poids corporel a été estimé à l‘aide d‘une formule barométrique. Les résultats montrent que les dromadaires mâles sont plus grands et plus lourds que les femelles pour toutes les mesures. L'analyse en composante principale et la classification ascendante hiérarchique ont permis de classer les femelles et les mâles en quatre groupes distincts. Les dromadaires d‘El Oued sont les plus lourds. Il existe une diversité de couleurs, dont la couleur Hamra est prédominante. Ces résultats sont prometteurs pour l‘avenir de l‘élevage camelin en Algérie et pour la préservation de cet héritage génétique unique

This study focused on dromedaries belonging to the Sahrawi and Targui populations, sampled from three regions of the northern Algerian Sahara: Ouargla, El Oued, and Ghardaïa. The main objective of the study was to characterize these two populations at the phenotypic, morphometric, and genetic levels, as well as to evaluate the relationships between live weight and the different body parameters, in order to optimize breeding practices of the Algerian dromedary. Morphometric measurements, comprising sixteen parameters measured using a retractable measuring tape, along with blood sampling, were carried out during the period from December 2022 to September 2023. In total, 219 dromedaries were phenotypically studied, including 150 Sahrawi individuals (84 in Ouargla, 26 in Ghardaïa, and 40 in El Oued) and 69 Targui individuals (20 in Ouargla, 30 in Ghardaïa, and 19 in El Oued), aged between 4 and 22 years. A representative subset of the same sample, comprising 157 animals, subsequently underwent blood collection and genomic DNA extraction. The results showed that the “Hamra” coat color was dominant in both populations, reflecting selective adaptation to the desert climate and a historical preference among breeders. Comparison of morphometric characteristics revealed significant differences between the Sahrawi and Targui populations. Sahrawi dromedaries are characterized by a robust and massive body conformation, indicating an aptitude for carrying heavy loads and for efficient milk or meat production. In contrast, Targui dromedaries exhibit a more slender morphology, suggesting a functional adaptation to speed. Principal Component Analysis (PCA) revealed positive and significant correlations among several morphometric parameters in the Sahrawi population, reflecting harmonious body development and morphological balance. Conversely, in the Targui population and in the combined sample, some correlations were positive while others were negative, suggesting more complex growth trajectories. Hierarchical Ascending Classification (HAC) identified four classes within the Sahrawi population, three classes within the Targui population, and four classes in the combined dataset. Factor analysis highlighted distinct grouping structures according to sex and population type. Chest girth proved to be a reliable indicator of live weight, although its effectiveness varied according to sex, age, geographic region, and population type. Sex, age, and population type had a significant effect on live weight in both populations. Geographic region significantly affected live weight in the Sahrawi population but not in the VI Targui population. Conversely, coat color had no statistically significant effect on live weight in either population. From a genetic perspective, a representative collection of genomic DNA was established and designated for genotyping, enabling a better understanding of the genetic heritage of Algerian camels and supporting the development of sustainable strategies for the conservation and valorization of these unique animal genetic resources