ABSTRACT The objective of this study was to quantify linear and angular morphological measurements of male and female horses participating in the Freio de Ouro competition. This study represents the first scientific evaluation of the biometrics of the Criollo breed, providing essential information for the evaluation of the development of the breed and supporting objective selection. We examined linear and angular measurements of 634 Criollo horses participating in the Freio de Ouro competition in 2011 and 2012, including height, chest circumference, cannon bone circumference, body length, metatarsus length, croup length, chest width, head length, dorsal neck length, throat circumference, and angles of the croup, scapula, and hock. Statistical analysis showed that males had a greater average cannon bone circumference (19.76 cm) than females (18.95 cm) and a greater throat circumference (77.66 cm for males and 73.30 cm for females). None of the other traits evaluated differed between genders. The average height (141.73 cm for males and 141.41 cm for females) was close to the minimum requirement for the breed standard. Subjective observations suggesting that animals of this breed are decreasing in size were not confirmed in this study, as the height and other evaluated measures did not differ between competing horses less or more than seven years of age. Although these measurements in isolation do not indicate the qualities of individual animals, they serve as valuable auxiliary elements for selection work, showing breed tendencies and providing objective data to support technical decisions of judges regarding conformation.

ABSTRACT This study used path analysis to establish the direct, indirect, and total effects of body linear and angular measurements on subjective morphological scores of the 247 Criollo horses that participated in their most important performance event, Freio de Ouro, in 2012. Freio de Ouro is the only event of the Criollo breed that considers morphology. Measurements of wither height, thoracic girth, cannon bone girth, body length, metatarsus length, croup length, shoulder width, head length, neck length, and upper neck girth, and the angles of rump, shoulder, and hock were taken. These morphometric measurements collectively explained 83% of the variation in morphological score. The measurements with the greatest total effects on score were neck length (correlation coefficient = 0.2300), upper neck girth (0.2100), angle of rump (–0.1600), thoracic girth (0.1400), shoulder width (0.1400), body length (0.1100), croup length (0.1100), shoulder angle (–0.1100), and metatarsus length (0.1000). These results mean that these variables have the highest association with morphological evaluation by referees. This is the first scientific study of the correlation of morphological measurements with judge evaluation in Criollo horses.

RESUMO: O presente estudo foi desenvolvido com o objetivo de se avaliar o efeito do sexo nos padrões de crescimento em potros da raça Crioula que possam servir de referência à sua criação, assim como base para futuros estudos em equinos dessa raça. Medidas de altura corporal, perímetro de tórax e perímetro de canela de 75 potros, pertencentes a três gerações, foram obtidas do nascimento aos três anos de idade, em duas propriedades no Rio Grande do Sul, Latitude 32°,33′,58″ e Longitude 53°,22′,33″. Em ambas as fazendas avaliadas, os animais eram mantidos no mesmo sistema de criação e manejo alimentar (extensivo e em regime de campo nativo). Foram realizadas análises de regressão não linear para se estimar as curvas de crescimento para as três características estudadas. Os resultados do presente estudo indicam diferença significativa (P<0,001) no crescimento da canela entre machos e fêmeas, sendo maior nos machos. As curvas preditas com modelos não lineares para a altura corporal e perímetro de tórax não apresentaram diferenças estatísticas entre os sexos. Para todas as características estudadas, a maior taxa de crescimento foi obtida ao primeiro ano de vida (altura corporal = 74%, perímetro de tórax = 76% e perímetro de canela = 63% em machos e 83% em fêmeas). Os resultados do presente estudo indicam que a evolução da altura corporal e perímetro de tórax em potros até os três anos de idade pode ser avaliada através de modelos não lineares e de maneira simultânea para machos e fêmeas. Por outro lado, o perímetro de canela deve ser modelado separadamente para cada sexo.

ABSTRACT: The objective of the present study was to evaluate the effect of gender on the growth of Criollo foals, in order to use this information as a reference for breeding as well as in future research. Body height, thoracic perimeter, and cannon bone perimeter of 75 foals were measured from two farms in Rio Grande do Sul, Brazil (Lat. 32°, 33′, 58″, Long. 53°, 22′, 33″) and from three generations over three years. In both farms, animals were kept under the same range and feeding conditions. Nonlinear regression models were applied to describe the growth curves for the three traits over the experimental period. Cannon bone perimeter was greater in males than in females (P<0.001) but the predicted curves for body height and thoracic perimeter did not differ between genders. For all traits, the highest rate of increase was achieved in the first year of life (body height = 74%, thoracic perimeter = 76%, and cannon bone perimeter = 63% for males and 83% for females). Results of this study indicated that changes in body height and thoracic perimeter can be predicted using nonlinear models in both male and female foals, until they reach three years of age; whereas, changes in cannon bone perimeter should be modeled separately for each gender.

RESUMO: A América do Sul possui um grande número de criatórios da raça Crioula, no entanto, há uma carência de informações sobre o desenvolvimento natural dos cascos dos potros, tornando a identificação de períodos ideais para o casqueamento corretivo uma dúvida frequente entre os criadores. Portanto, o objetivo deste estudo foi realizar a biometria natural (do nascimento aos 8 meses) no casco de 46 potros da raça Crioula. Os resultados indicaram uma taxa de crescimento mais rápido nos primeiros 4 meses, com subsequente desaceleração até o desmame. O crescimento médio do casco foi em média 0,21cm mo-1, enquanto o comprimento do talão foi de 0,14cm mo-1. Não foram observadas diferenças significativas no equilíbrio médio/lateral do casco ou entre os membros durante o período experimental. O perímetro da banda coronária e a largura solar do casco apresentaram um crescimento médio de 0,97 e 0,46cm mo-1, respectivamente, e foram altamente correlacionados (r=0,99, P≤0,01). A idade dos potros foi a característica mais correlacionada positivamente, seguida da largura solar, do comprimento do casco e do perímetro da banda coronária. Nós concluímos que o crescimento do casco em potros da raça Crioula foi mais intenso durante os quatro primeiros meses de vida.

ABSTRACT: South America has numerous Criollo horse breeding farms; however, information on foal hoof growth is still limited and identifying the ideal periods to apply corrective trimming is a frequent concern for horse owners. In the present study, a morphometric analysis of hoof growth was performed on 46 Criollo foals from birth to weaning (0-8 months). Results showed that hoof growth rate was higher in the first four months followed by a decrease until the eighth month. Average growth rate of the hoof was 0.21cm per month, whereas that of the heel was 0.14cm per month. However, no significant differences were observed between medial and lateral heel length or between limbs. Coronary band perimeter and solar width showed an average increase of 0.97cm and 0.46cm per month, respectively, and were significantly correlated (r=0.99, P≤0.01). The characteristic most positively correlated to biometric variables was foal age, followed by solar width, toe length, and coronary band perimeter. In conclusion, hoof length increase in Criollo foals was more intensive during the first four months of life.