Morphometric measurements for sexual dimorphism in the Campolina horse breed

Abstract: The objective of this work was to distinguish the sexual dimorphism of horses of the Campolina breed, by morphometric measurements, and to classify them according to sex, using discriminating functions. Two-hundred and fifteen horses were measured, and 39 morphometric measurements were evaluated. The analysis of covariance and the discriminant analysis were performed. Males were taller and showed a wider chest, a greater scapular-humeral angle, and a larger neck, both in length and circumference. Females had a larger heart girth, wider hips, and a greater opening of the coxal-ground and femorotibial angles. Regarding classification, circumference measurements (85.58%) were more accurate in sexual differentiation than the linear (83.26%) and angular (73.02%) ones. As to classification error, of the total animals measured, 10 to 20% of the females were categorized as males. In addition, 11 to 38% of the males were categorized as females. It can be concluded that of the 39 morphometric measurements evaluated, 22 are responsible for sexual dimorphism in the Campolina horse breed. Circumference and linear measurements provide a more assertive classification to determine sexual dimorphism. Angular measurements show greater classification errors regarding the gender of the horses.

摘要：本研究旨在通过形态测量手段区分卡波里纳马（Campolina）品种的性别二态性，并借助判别函数按性别对个体进行分类。本研究共测量215匹卡波里纳马，评估了39项形态学测量指标，采用协方差分析与判别分析开展数据分析。结果显示，公马体型更高，胸廓更宽，肩胛-肱骨夹角更大，颈部长度与围度均更突出；母马则具备更大的心脏围度、更宽的髋部，以及更大的髋-地面夹角与股胫夹角。在性别分类准确率方面，围度测量（85.58%）的区分精度高于线性测量（83.26%）与角度测量（73.02%）。从分类误差来看，在所测量的全部个体中，10%至20%的母马被误判为公马，另有11%至38%的公马被误判为母马。综上，在所评估的39项形态测量指标中，有22项与卡波里纳马的性别二态性相关；围度与线性测量可实现对性别二态性的更精准分类，而角度测量在马匹性别判别中存在更高的分类误差。