Genetic analyses of coat colors are frequently restricted to subjectively categorized phenotype information. The aim of this study was to develop a method to numerically quantify the variability of leopard complex (LP) spotting phenotypes introducing tools from image analysis. Generalized Procrustes analysis eliminates systematic errors due to imaging process. The binarization of normalized images and the application of principal component analysis (PCA) on the derived pixel matrices, transform pixel information into numerical data space. We applied these methods on 90 images to ascertain the specific leopard patterns within the Noriker breed. Furthermore, we genotyped a representative sample of 191 Noriker horses for the known LP spotting associated loci. Ninety-seven percentage of the genotyped leopard spotted horses were heterozygous for LP and had at least one copy of the PATN1 allele. However, the remaining pattern variation was great, indicating other genetic factors influencing the expression of LP spotting. Based upon this data, we estimated effect sizes of the modifier PATN1, and additional factors including sex, age, base color, and spotting phenotype of parents. The PCA of the pixel matrix resulted in 2 significant components accounting for 51% of the variation. Applying a linear model, we identified significant effects for age groups and base color on the first and second components, while for sex and parents’ LP phenotype significant effects were found on 4 additional component.

Article: Druml T., Grilz-Seger G., Neuhauser B., Neuditsko M., Gottfried Brem; Phenotypic and Genetic Analysis of the Leopard Complex Spotting in Noriker Horses. J Hered 2017. https://doi.org/10.1093/jhered/esx039

 

 

In dieser Arbeit wurde die genetische Variabilität der österreichischen Haflingerpopulation anhand einer Pedigree-Analyse untersucht. Für die Berechnung der Diversitätskennzahlen und der Inzuchtkoeffizienten wurden drei zeitlich abgegrenzte Referenzpopulationen gebildet, die als zuchtaktive Tiere mit eingetragenen Nachkommen im Hauptstutbuch definiert waren. Für die 2.560 zuchtaktiven Pferde im Zeitraum von 1978 bis 1985 (Referenzpopulation 3) wurde ein durchschnittlicher Inzuchtkoeffizient von 6,34 %, respektive 43 effektive Gründertiere und 18 effektive Ahnen ermittelt. Diese Diversitätskennzahlen entwickelten sich in den beiden darauffolgenden Referenzpopulationen (R2 1993 bis 2000; R3 2008 bis 2015) negativ. Während der Inzuchtkoeffizient mit 8,83 % in R2 und 11,92 % in R1 sukzessive zunahm, verringerte sich die Anzahl der effektiven Gründertiere auf 35 in R2 und auf 31 effektive Gründertiere in R1. Im gleichen Zeitraum sank die effektive Anzahl an Ahnen von 14 in R2 auf 12 in R1. Der Genpool der aktuellen österreichischen Haflingerzuchtpopulation setzt sich zu 6,9 % aus arabischen Genen, 1,7 % Gidran Genanteil, 1,8 % Noriker Genanteil, 58,6 % Genanteil von Original Haflingerstuten (Ohast.), 24,1 % Genanteil von Haflingerpferden und 0,01 % Genanteil von Kreuzungsstuten zusammen und 6,9 % der Gene gehen auf eine Galizische Landesstute zurück. Zusammenfassend zeigt die Abnahme der genetischen Variabilität und die mittlere Inzuchtsteigerung von über einem Prozent pro Generation in der österreichischen Haflingerzucht eine zunehmende Verengung des Genpools, der durch eine Förderung von derzeit züchterisch ungenutzten und in niedrigen Frequenzen vorkommenden Gründergenomen entgegengewirkt werden soll.

Quelle: Züchtungskunde. 2016; 88(5): 379-394.

AutorInnen: Thomas Druml, Katharina Sauer, Julia Elsbacher, Gertrud Grilz-Seger, Gottfried Brem

 

 

The aim of this study was to determine the allele frequency of the glycogen synthase 1 (GYS1) mutation associated with polysaccharide storage myopathy type 1 in the Austrian Noriker horse. Furthermore, we examined the influence of population substructures on the allele distribution. The study was based upon a comprehensive population sample (208 breeding stallions and 309 mares) and a complete cohort of unselected offspring from the year 2014 (1553 foals). The mean proportion of GYS1 carrier animals in the foal cohort was 33%, ranging from 15% to 50% according to population substructures based on coat colours. In 517 mature breeding horses the mutation carrier frequency reached 34%, ranging on a wider scale from 4% to 62% within genetic substructures. We could show that the occurrence of the mutated GYS1 allele is influenced by coat colour; genetic bottlenecks; and assortative, rotating and random mating strategies. Highest GYS1 carrier frequencies were observed in the chestnut sample comprising 50% in foals, 54% in mares and 62% in breeding stallions. The mean inbreeding of homozygous carrier animals reached 4.10%, whereas non-carrier horses were characterized by an inbreeding coefficient of 3.48%. Lowest GYS1 carrier frequencies were observed in the leopard spotted Noriker subpopulation. Here the mean carrier frequency reached 15% in foals, 17% in mares and 4% in stallions and inbreeding decreased from 3.28% in homozygous non-carrier horses to 2.70% in heterozygous horses and 0.94% in homozygous carriers. This study illustrates that lineage breeding and specified mating strategies result in genetic substructures, which affect the frequencies of the GYS1 gene mutation.

AutorInnen: Thomas Druml , Gertrud Grilz-Seger, Markus Neuditschko, Gottfried Brem , ArticleinAnimal Genetics · July 2016,DOI: 10.1111/age.12481

 
 
 

The aim of this study was to investigate the effect of glycogen synthase 1 (GYS1) mutation on performance traits in Noriker draft horse stallions. Individual scores of 32 performance traits and the final performance score were obtained from 169 stallions that took part in the standardized stationary 30-day performance test throughout the years 2002 to 2014. In 2014 the stallions have been genotyped for the GYS1 mutation resulting in 105 non-mutation-carriers, 57 heterozygous, and 7 homozygous animals. The mean frequency of animals carrying the mutation was 38 % (64 of 169). The final performance score and 32 single performance traits were analyzed using a linear model including the GYS1 mutation genotype, the testing year and age as fixed effects. For the final performance score no effect of the GYS1 mutation was found. In three single traits – driving ability, drafting manner, and kindness in the discipline heavy-load lodging – significantly lower scores for heterozygous horses than for non-carrier animals were obtained. Homozygous animals did not differ significantly from both groups. Our results from this retrospective study suggest no effect of the GYS1 mutation on performance traits and on the final performance score.

Citation : Druml, T., Grilz-Seger, G., and Brem, G.: Effect of the glycogen synthase 1 (GYS1) mutation on performance traits in 169 Noriker draft horse stallions – a retrospective study, Arch. Anim. Breed., 59, 453-459, doi:10.5194/aab-59-453-2016, 2016.

 

 

The pedigree of the current Austrian Noriker draught horse population comprising 2808 horses was traced back to the animals considered as founders of this breed. In total, the number of founders was 1991, the maximum pedigree length was 31 generations, with an average of 12.3 complete generations. Population structure in this autochthonous Austrian draught horse breed is defined by seven breeding regions (Carinthia, Lower Austria, Salzburg, Styria, Tyrol, Upper Austria and Vorarlberg) or through six coat colour groups (Bay, Black, Chestnut, Roan, Leopard, Tobiano). Average inbreeding coefficients within the breeding regions ranged from 4.5% to 5.5%; for the colour groups, the coefficients varied from 3.5% to 5.9%. Other measures of genetic variability like the effective number of founders, ancestors and founder genomes revealed a slightly different genetic background of the subpopulations. Average coancestries between and within breeding areas showed that the Salzburg population may be considered as the nucleus or original stock whereas all other subpopulations showed high relationship to horses from Salzburg. The target of draught horse breeding in the 21st century does not meet the breeding concept of maximizing genetic gains any more. Stabilizing selection takes place. In this study, we show that demographic factors as well as structure given by different coat colours helped to maintain genetic diversity in this endangeredhorse breed.

Thomas Druml et al. J. Anim. Breed. Genet. 126 (2009) 348-356

 

 

The quality of individual ratings of conformation traits can commonly be evaluated by calculating inter-rater correlations and repeatability coefficients. We present an approach in which we associate the individual rating scores with the underlying horse shapes derived from standardized images, performing a shape regression. Therefore, we analyzed the shape of 102 Lipizzan stallions from the Spanish Riding School in Vienna, defined by 246 shape-correlated two-dimensional coordinates using techniques from the field of image analysis and geometric morphometrics. In addition we examined the differences in the conformation classifiers' perceptions of type traits and functional traits. In this study part, the rating scores of eight conformation classifiers were tested for agreement, yielding inter-rater correlations ranging from 0.30 to 0.55 and kappa coefficients ranging from 0.08 to 0.42. From the 12 scoring traits assessed on a valuating scale, type traits with a mean kappa coefficient (κ) of 0.27 demonstrated a higher agreement than functional traits (κ  =  0.14). Based on 246 two-dimensional anatomical and somatometric landmarks, the shape variation was analyzed by the use of generalized orthogonal least-squares Procrustes (generalized Procrustes analysis – GPA) procedures. Shape variables were regressed into the results from visually scored linear type trait classifications (shape regressions). From the 48 performed shape regressions (eight classifiers, six traits), 42 % resulted in a significant equation. In 58 % of the ratings, no association between scores and the phenotype of the horses was found. Phenotypic differences of model horses along significant regression curves of mean ratings and individual ratings were exemplarily visualized and compared by warped and averaged images. Finally, we demonstrated that the method of shape regression offers the possibility to evaluate the association of individual ratings from expert conformation classifiers with the shapes of horses. The detected bias in classifiers' rankings have not been considered in breeding programs, and its impact on selection procedures still needs further research.

Citation: Druml, T., Dobretsberger, M., and Brem, G.: Ratings of equine conformation – new insights provided by shape

Arch. Anim. Breed., 59, 309-317, 2016 http://www.arch-anim-breed.net/59/309/2016/ doi:10.5194/aab-59-309-2016