Genetisk analys av data från fölbesiktning och jämförelse med resultat vid treårstest

Abstract: More than 1000 Swedish Warmblood foals are shown every year at foal inspections which are arranged around the country. Six traits are evaluated at these inspections: type, head-neck-body, correctness of legs, walk, trot and canter. No previous genetic studies have been done on the data from these evaluations. The purpose of this study was to do genetic analyses of the traits which are evaluated at foal inspections. The purpose was also to see if there are any correlations between the results of the foal inspections and the results from the tests of three-year-old horses. The results from this study are supposed to provide a basis for a proposal of possible changes in the regulations of the foal evaluations. In the study, results from foal inspections from the years 2002-2006 (4861 horses) and results from tests of three-year-old horses from the years 1999-2007 (8283 horses) were analysed. 1251 horses had results from both occasions. Heritabilities were estimated for traits evaluated at both foal inspections and the tests of three-year-olds. Genetic and phenotypic correlations were estimated between traits evaluated at foal inspections, between those traits that were evaluated at both evaluations and between the traits from the foal inspections and the free jumping traits from the tests of the three-year-old horses. A comparison was done between breeding values estimated from the total scores of the foals and the BLUP-index (dressage index and jumping index) for stallions with 15 or more evaluated progenies. The estimated heritabilities for foals varied from very low for correctness of legs (0.02) to moderate for type, head-neck-body and walk (0.27-0.38) to high for trot, canter, total score and class (0.42-0.77). The heritabilities for the traits from the tests of three-year-old horses were in the same range. Moderate heritabilities were estimated for both the free jumping traits. The genetic correlations between traits evaluated on foals were all highly positive (0.43-0.98). Between those traits that were evaluated both on foals and three-year-old horses, the genetic correlations were high (0.86-1.00). Canter was the trait evaluated on foals that had the strongest correlation with the free jumping traits of the tests of the three-year-old horses (0.31-0.34), whereas the other correlations were around zero. The comparison between the BLUP-index and breeding values for total score as foal showed a positive correlation (0.60) between the breeding value and the dressage index but a negative correlation (-0.31) with the jumping index. The study showed that the whole scale was not used, neither were all the classes. There were clearly positive correlations between the results of the foals and the results of the three-year-old horses concerning type and gaits, but the correlations with the free jumping scores were practically non-existent. A simplified classification should probably be considered, and it is important to clarify that the foal results should not be taken in such consideration that it leads to a neglect of the breeding of jumping horses. An idea would be to include pedigree-indexes (BLUP) into the evaluations and thereby classify the foals for both dressage and jumping. The foal inspections are anyway valuable because they offer an opportunity to market foals, for counseling the owners and they also contribute to an early handling of the foals.