Estimation of heritability of Lipizzaner horses for morphological traits by means of various methods

Heritability of morphological traits of Lipizzaner horses in Croatia was estimated by various methods. Heritability for withers height, obtained by the method of intraclass correlation, was somewhat higher (h2=0.32) compered to the method of regression and the REML method (h2=0.29 and 0.26, respectively). The same was estimated for chest girth and cannon bone circumference. For the three investigated traits the variance within sires was higher than the variance between sires. The heritability obtained by the ML method for the withers height of mares exceeds the heritability estimated by the REML method for 0.01. For the chest girth, the estimated heritabilities by the ML and REML method show the same value. The heritability of the cannon bone circumference of mares estimated by the ML method is 0.02 higher than the heritability estimated by the REML method. The average heritability for body measurements at foaling and at six months of age increased with the increase of foaling number. For the first and second foaling heritability was h2=0.27, and for the firs to the fifth foaling it was h2=0.34. The same trend was found for the heritability level of chest girth and cannon bone circumference at foaling and at six month of age. This points to slightly higher influence of genetic factors upon variability of the analysed morphological traits in later foalings.