engleski

Genetic analysis of the withers growth in Lipizzan horse using random regression

Longitudinal records of the withers height (taken at birth, six, 12, 24 and 36 months of age) were analyzed for 879 Lipizzan horses born in Croatia between 1931 and 1999. The corresponding pedigree file consisted of 5010 horses. Covariance functions were estimated by using bivariate animal models with ages defined as separate traits and by using random regression model directly on data. In all models, sex, age of dam and interaction stud- year-season were considered as fixed effects while individual horses and residual errors were considered as random effects. The random regression model also included permanent environment effect due to repeated measurements. Polynomial functions of order three were adequate to explain additive genetic functions. Estimated heritabilities from bivariate and random regression models ranged from 0.14 to 0.25 and from 0.12 to 0.23, respectively. While genetic correlations between longitudinal records ranged from 0.76 to 0.99, corresponding phenotypic correlations ranged from 0.12 to 0.49. Overall, the estimated covariance functions from this study demonstrated heterogeneity of covariances of wither height in Lipizzaner horse and proved to be adequate in estimating covariances and correlations between heights at any two age points from birth to 36 months of age.

Lippizan horse ; growth ; random regression

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