In this experiment, which is based on a cohort of 44 Lipizzan mares from the Austrian state stud farm of Piber, we present new statistical techniques for the analysis of shape and equine conformation using image data. In addition, we examined which strategies and procedures of image processing techniques led to a successful interpretation of the traits implemented in horse breeding programs. A total of 246 two-dimensional anatomical and somatometric landmarks were digitized from standardized photographs, and the variation of shape has been analyzed by the use of generalized orthogonal least-squares Procrustes (generalized Procrustes analysis (GPA)) procedures. The resulting shape variables have been regressed on the results from linear type trait classifications. In addition, the rating scores of six conformation classifiers were tested for agreement, yielding an interrater correlation (inter-class correlation) ranging from 0.41 to 0.68, respectively, a κ coefficient ranging from 0.16 to 0.53. From the 12 linear type traits assessed on a valuating scale, only the type-related traits (type, breed-type and harmony) revealed significant (P < 0.05) results in the regression analysis of shape variables on linear type traits. The other nine traits were characterized by a lower agreement between classifiers and did not result in a significant 'shape regression'. Finally, the 'horse shape space' defined by shape variables resulting from GPA procedures offered the possibility to assist in trait definition and in the evaluation of ratings, and it is an adequate biological and objective scale to human perception of conformation, which is expressed in numerical data only.
Abstract. 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.
Abstract.Crossbreeding between individuals of different breeds and introgression, the transfer of genes between breeds and/or populations mediated primarily by backcrossing, have been characteristic tools used in the refinement or optimisation of practical horse breeding. In this study we analysed the genetic contribution of the Arabian horse to the gene pool of the Lipizzan horse and its association with the overall type via shape regression analysis in 158 Lipizzan horses from the Austrian federal stud farm of Piber and the Spanish Riding School. Although crossbreeding with Arabian horses took place between 1776 and 1945, we found a significant association between Lipizzan body shape (p < 0.003) and individual coefficients of Arabian gene proportion, which varied from 21 to 29 %. In order to compare and interpret the estimated Lipizzan shape transitions from Iberian type towards the oriental type, we included a sample of 32 Shagya Arabians from the Slovak National stud farm Topol'ćianky. The estimated shape transitions in Lipizzans due to an increasing proportion of Arabian genes are similar to those we observed in the population comparison study of Lipizzan and Shagya Arabian horses. The main morphometric differences due to increasing Arabian genetic contributions in Lipizzans were found in the conformation of head, neck, withers, and legs. Although selection in the Austrian Lipizzan breed favours the Iberian type, Arabian shape characteristics are still present, indicating the segregation of Arabian founder haplotypes in the population. We also demonstrated that techniques of shape analysis are able to differentiate phenotypes associated with the gene pool and can be applied for phenotypic evaluation and prediction in crossbreeding programs.
Summary About an Indirect Proof of Ovulation and Ovafertilisation in Dogs by Continued Controls of Plasma Progesterone Levels: In addition to already published data (Arbeiter et al., 1990) we could achieve important facts concerning the estimation of mating time of the bitch by measuring the progesterone (P4) level continuously and observing the clinical signs on a collective of 106 ambulant patients. We found that a P 4‐concentration of 5 ng/ml plasma and above is signalizing ovulation or ovafertilisation; a sudden rise of the progesterone over 10 ng (Ovucheck®), reflecting 19.2 ng/ml (Serozyme®‐Progesterone), turned out to be a diagnostic mark for determination of mating time. Copulation took place between the 9th and 19th day of heat. 89% of the controllable bitches (n = 79) conceived and birth occurred 61.4 days (x̄) later. The litter size and the loss of dead born puppies (4.7 %) was normal with regard to the pertinent races. Because of their easy handling the P 4‐testkits (Ovucheck®; Serozyme®‐Progesterone) are of good use for the practician. Zusammenfassung Bereits publizierte Untersuchungen weiterführend (Arbeiter u. Mitarb., 1990), konnten an 106 ambulant betreuten Patienten aufgrund von Progesteron‐Verlaufskontrollen im Verein mit den klinischen Befunden wesentliche Erkenntnisse für eine präzisere Bestimmung der Deckzeit bei der Hündin gewonnen werden. Es wurde ermittelt, daß ein P4‐Gehalt von 5 ng/ml Plasma und darüber die Freisetzung und nachfolgende Fertilisation der Ova anzeigt und das sprunghafte Ansteigen auf > 10 ng/ml (Ovucheck®) entsprechend 19,2 ng/ml (Serozyme®‐Progesteron), ein diagnostischer Richtwert für die Deckzeitbestimmung ist. Die Belegungen erfolgten zwischen dem 9. und 19. Tag der Läufigkeit; 89% der kontrollierbaren Hündinnen (n = 79) konzipierten und kamen nach 61,4 Tagen (x̄) zur Geburt. Die Wurfgrößen waren den Rassen gemäß, der Verlust an Totgeburten (4,7%) der Norm entsprechend. — Die einfach auszuführenden P4‐Messungen (Ovucheck®‐Schätzwerte; Serozyme®‐Progesteron‐Digitalmessung) machen die Verfahren auch für die Praxis geeignet.
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