Sexual Dimorphism in the Growth and Morphometric Allometry of the Santandereana Creole Goat Breed in Colombia

Animal growth involves changes in size with age and is associated with environmental factors. The aim was to conduct a study of a representative group of the Santandereana Creole goat breed to evaluate morphometric allometry according to sex. A sample of 23 males and 76 females, ranged 8–72 and 8–84 months of age respectively, was studied. Morphometric allometry was evaluated using 30 linear characters. A Mann–Whitney test assessed right- and left-side differences in horns (length and perimeter) and ears (length and width). A one-way PERMANOVA, using Gower distances, assessed sex differences. Principal component analysis (PCA) using a var-covar matrix identified the most discriminating traits. A one-way ANCOVA, using loadings at PC1, was performed to compare allometric trends between sexes. Differences between sexes were observed in linear traits (p = 0.0101) and indices (p = 0.0364). No differences were observed between the right and left sides in horns and ears. Differences were observed in size, with body weight, body length, thoracic perimeter, and horn length (right/left) being the most discriminating values reflecting sexual dimorphism of size. The indexes corroborated the larger size of males, especially in relation to skull width, rump length, chest depth, and body weight. Detected differences may reflect variations in the development of skeletal maturity. The indexes confirm that the Santandereana Creole goat is an animal with a tendency for meat production, with larger males and brachycephalic features due to the shape of the head. Discriminatory measures can be considered as parameters of interest for preserving the breed and establishing genetic improvement programs.