Defining a latent body size phenotype from morphometric traits in dromedary camels (Camelus dromedarius) using confirmatory factor analysis

This study defined a latent body size (BS) phenotype in dromedary camels (Camelus dromedarius) using morphometric measurements within a confirmatory factor analysis (CFA) framework. Morphometric records from 136 dromedary camels (8 males and 128 females) reared in southern Kerman province, Iran, were analyzed. Six morphometric traits, including height at hump (HH), body length (BL), height at withers (HW), thoracic depth (TD), abdominal girth (AG), and abdominal depth (AD), were considered as observed indicators of the latent BS construct. The CFA model was fitted using robust maximum likelihood estimation in the lavaan package of R. Model adequacy was assessed using the comparative fit index (CFI), Tucker–Lewis index (TLI), root mean square error of approximation (RMSEA), and standardized root mean square residual (SRMR). The model demonstrated acceptable fit (CFI = 0.94; TLI = 0.91; RMSEA = 0.06; SRMR = 0.05). Standardized factor loadings ranged from 0.66 to 0.87 and were significant for all traits ( P < 0.001), indicating that the selected morphometric variables effectively represented the underlying BS latent construct. AG exhibited the highest factor loading (0.87), followed by BL and TD (0.80 each). Pearson’s correlations among morphometric traits and between traits and BS were positive and significant ( P < 0.001 ). The highest correlation was observed between AG and BS (0.79). The results demonstrated that the latent-variable framework effectively captured the shared biological variation among morphometric traits and provided a biologically meaningful composite representation of body size. The proposed latent BS phenotype may provide a robust and biologically meaningful composite trait for phenotypic evaluation and may have potential applications in breeding programs, and future genetic and genomic analyses in dromedary camels, although these applications require further investigation through quantitative genetic studies.