Nongenetic effects and genetic parameters of the limb measurements in Iranian Turkoman horses / Efeitos não genéticos e parâmetros genéticos das medidas dos membros em cavalos turcomanos iranianos

From the past to now, body conformation is an instrument for the Iranian horse judging. This research aimed to study and estimate the genetic and nongenetic parameters of limb conformation traits in the Iranian Turkoman horses. Therefore, body conformation traits, specifically limb conformation, of 1273 horses were measured. Among the horses studied, 357 stallions and 916 mares were included. For studying the nongenetic (such as sex, province and birth year) and genetic effects (such as additive genetic effect), the LSMEANS procedure and the restricted maximum likelihood method (REML) were used by SAS and MATVEC software, respectively. Birth year had a significant effect on most of the traits, especially scapula length and arm length (P < 0.05). The lowest and the highest heritability was estimated for femur length (0.11 ± 0.03) and forearm length (0.40 ± 0.09), respectively. Overall, considering the heritability estimations, the expectation is that limb conformation traits will have a good response to the selection and genetic progress. Farmers can choose the best stallions and mares based on the traits mentioned, so that their foals can have good body conformation.(AU)

Do passado para o presente, a conformação corporal é um instrumento para o julgamento de cavalos iranianos. Esta pesquisa teve como objetivo estudar e estimar os parâmetros genéticos e não genéticos das características de conformação dos membros nos equinos turcomanos iranianos. Portanto, as características de conformação do corpo, especificamente a conformação dos membros de 1273 cavalos foram medidas. Entre os cavalos estudados, 357 garanhões e 916 éguas foram incluídos. Para estudar os não genéticos (como sexo, província e ano de nascimento) e efeitos genéticos (como efeito genético aditivo), o procedimento LSMEANS e o método de máxima verossimilhança restrita (REML) foram utilizados pelo software SAS e MATVEC, respectivamente. O ano de nascimento teve um efeito significativo na maioria das características, especialmente comprimento da escápula e comprimento do braço (P < 0,05). A menor e mais alta herdabilidade foi estimada para o comprimento do fêmur (0,11 ± 0,03) e comprimento do antebraço (0,40 ± 0,09), respectivamente. No geral, considerando as estimativas de herdabilidade, a expectativa é que as características de conformação do membro tenham uma boa resposta à seleção e progresso genético. Os agricultores podem escolher os melhores garanhões e éguas com base nas características mencionadas, para que seus potros possam ter uma boa conformação corporal.(AU)

Study of factors affecting the body conformation traits of Iranian Turkoman horses.

The Iranian Turkoman horse is considered one of the major categories of Iranian native horses. The aim of this research was to study the genetic and nongenetic factors affecting body conformation traits in Iranian Turkoman horses. For this, measurements were performed on body conformation traits of 121 horses. To study the effect of nongenetic factors, the Lsmeans procedure was used. Variance components and heritability were estimated by restricted maximum likelihood method (REML) and AI-REML convergence algorithm. The standard deviation was estimated to be 7.04 cm for croup depth and 2.08 cm for chest width, and the coefficient of variation was estimated to be 11.27% for croup length and 2.58% for withers height. Sex had a significant effect on head-neck circumference (P<0.05), withers height (P<0.05), chest width (P<0.05), and croup height (P<0.05). Province had a significant effect on withers height (P<0.05) and croup depth (P<0.05). The lowest and highest heritability estimates were for head-neck circumference (0.12 ± 0.06) and neck-body circumference (0.33 ± 0.09), respectively. The lowest and highest additive genetic variance estimates were for head length (0.64) and pelvis width (18.34), respectively. Generally, the medium to high estimated heritability for the traits in this study indicate that genetic improvement would be possible in these traits.