Estimation of genetic parameters and trends for morphometric traits in Brazilian Mangalarga Marchador horses

The objective of this work was to estimate genetic parameters and evaluate genetic trends over 26 years for morphometric traits in Mangalarga Marchador horses. Twelve morphometric traits were evaluated (withers and croup heights; length of head, body, shoulder, croup, neck, back, and loins; width of head and croup, and cannon bone and thorax perimeters). These traits were evaluated in 38,341 animals born between 1987 and 2012 and with a relationship matrix of 77,719 animals. Gibbs sampler was used to obtain samples of the posterior distributions of genetic parameters under animal models. Genetic trends were estimated by regression of estimated breeding values in function of birth year. The heritabilities of all traits were moderate to high and ranged from 0.27 to 0.48. However, the additive genetic coefficients of variation were low, ranging from 1.23 to 3.82%. The genetic trends of all the studied traits were significant, but of low magnitude. Negative genetic trend was observed for body length, while positive genetic trends were estimated for the other 11 traits. Although additive genetic differences accounted for a significant part of the phenotypic differences, genetic gains in the population were limited by low phenotypic variability. Therefore, it is necessary to develop data collection strategies to increase phenotypic and genetic variability in the population, such as the inclusion of animals that do not meet breed standard, but which have parents registered in the breeders' association, in the database.

Medidas lineares e angulares de animais da raça Quarto de Milha utilizados em uma prova de vaquejada / Linear and angular measurements of animals race Quarter Horse used in a proof vaquejada

Objetivou-se com este trabalho avaliar as medidas lineares e angulares de animais da raça Quarto de Milha utilizados em provade vaquejada. Foram mensurados 98 animais, sendo 70 machos e 28 fêmeas da raça Quarto de Milha. Foram coletadas asinformações de 25 medidas lineares e 9 medidas angulares. As análises estatísticas foram realizadas utilizando-se o pacoteestatístico SISVAR, sendo os dados submetidos a teste de SNK a 5% de probabilidade.Verificou-se diferença significativa (P<0,05)entre os sexos apenas para as medidas lineares e angulares do comprimento do dorso-lombo, perímetro da canela posterior epara ângulo escapuloumeral. As fêmeas apresentaram maior dorso-lombo (50,64 e 47,31cm) e maior angulo escápulo-umeral(91,31 e 87,99 graus) enquanto os machos tiveram maior perímetro da canela (20,26 e 19,64cm). Os animais da raça Quartode Milha utilizados em vaquejadas possuem medidas lineares similares entre os sexos. As conformações corporais nos equinosQuarto de Milha favorecem as exigências funcionais desse esporte.(AU)

The of work aims to evaluate the linear and angular measurements of Quarter Horse breed animals were in proof vaquejada.Measured were 98 animals being 70 males and 28 females of the breed Quarter Horse. Were collected the information of 25linear and measures 9 measures angular. The statistical analyses were conducted using the statistical package SISVAR, being thedata submitted by SNK test at 5% of probability. There was significant difference (P <0.05) between the sexes only for linear andangular measurements of length the back-loin, rear perimeter of cinnamon and scapulohumeral angle. Females showed greaterdorsal rib (50.64 and 47,31cm) and greater angle scapulohumeral (91.31 and 87.99 degrees) while males had higher perimeter ofcinnamon (20.26 and 19.64cm). The animals of the Quarter Horse used in vaquejada have similar linear measurements betweenthe sexes. The body conformations in Quarter Horse favor the functional demands of the sport.(AU)