Accuracy of Image Analysis for Linear Zoometric Measurements in Dromedary Camels

Abstract The present study consisted in verifying the effectiveness of the image analysis method for body measurement in dromedary camel compared to manual measurements as a reference method. To do this, twenty-one linear body measurements were estimated on 59 adult Sahraoui dromedary camels (22 males and 37 females) with normal clinical condition by the standard method using a measuring stick or vernier caliper. Image analysis on profile, front or behind photographs were processed using Axiovision Software. Overall; mean comparison, relative error, variance, Pearson's correlation coefficient and coefficient of variance showed that the image analysis method is accurate in relation to the manual measurement. Furthermore, image analysis results indicated relevant accuracy (bias correction factor, Cb ≈1) and precision (Pearson ρ ≈ 1) which were significantly correlated with the results of the reference method (Lin's concordance correlation coefficients rccc ≈ 1). According to Blant Altman upper and lower limits of agreement, the concordance was estimated between 93.22 and 98.3%. Passing-Bablok regression showed good relationship between results of the two methods displaying no significant systematic and proportional bias. The image analysis method for linear body measurements in dromedary camel yielded results that are in agreement with the manual measuring method. This method is a valid tool for studies on camel conformation traits.