Factor analysis of body measurements in Arabian horses

Data of 13 body measurements have been analysed from 166 Arabian horses, 123 mares and 43 stallions, ranging from 49 to 298 months of age, belonging to Alzahraa stud, Cairo, Egypt. General linear model was used to study age and gender effects on these measures. Gender was a significant source of variation for most studied traits, but not for neck girth, cannon bone circumference of fore and hind legs, and pastern girth of fore and hind legs. Age significantly affected pastern girths of fore and hind legs and cannon bone circumference of fore legs, while there was no significant effect on the other measurements. Pearson correlations, adjusted for age effect, between measurements were estimated and ranged from 0.02 to 0.84 for mares and from -0.05 to 0.90 for stallions. Factor analysis with promax rotation for each gender was carried out to derive fewer independent common factors. Three factors were extracted which accounted for 66% and 67% of the total variance in mares and stallions respectively. The first, second and third factors in mares tended to describe body thickness, leg thickness and general size respectively; whereas in stallions they tended to differentiate among general size, leg thickness and body thickness respectively. The three extracted factors for each gender determine the main sources of shared variability that control body conformation in Arabian horses. These factors could be considered in selection programmes to acquire highly coordinated bodies in pure Arabian horses with fewer measurements.