Science

Allometric scaling of equids (Equus caballus) in a continuum of body sizes
Alana N. Walker
Dr. Charlie Apter and Dr. Dean DeCock, Faculty Mentors

Allometry (size-dependent deviation from geometric similitude) has been applied to select mammals but not to modern horses (Equus caballus). This study reports morphologic allometric relationships across an equine body size continuum. Body mass and seven distinct measurements (withers height, croup height, pelvic width, leg length, pastern circumference, body length, heartgirth) were obtained for 222 horses. Double-logarithmic plots in the form y=ax^b were generated using least-squares regression. Comparisons both within body type and across the intraspecies continuum revealed slightly negative allometry between withers and croup height (b=0.949, R²=0.997, p=0.007), and positive allometry between mass and heartgirth (b=1.378, R²=0.99, p=0.012). No intraspecies sexual dimorphisms nor miniature horse morphological reorganization was evident. Human selection is apparent in breeding stallions; however, none were statistical outliers. Allometric relationships remain stable within the sampled population despite an eleven-fold mass increase. These findings suggest that there is a consistency of morphology among all equids.

Keywords: horse, allometry, body proportions, allometric scaling, biometry

Topic(s):Agricultural Science

Presentation Type: Oral Paper

Session: 40-1
Location: VH 1432
Time: 1:15

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