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Topic:Principal Component Analysis
Principal Component Analysis (PCA) is a statistical technique used to simplify complex datasets by reducing their dimensionality while preserving as much variance as possible. In equine research, PCA can be applied to various types of data, including genetic, physiological, and performance metrics, to identify patterns and relationships that may not be immediately apparent. By transforming original variables into a new set of uncorrelated variables called principal components, researchers can effectively analyze and interpret large datasets. PCA facilitates the identification of key factors influencing traits or conditions in horses, aiding in areas such as genetic studies, disease susceptibility, and performance optimization. This page compiles peer-reviewed research studies and scholarly articles that explore the application, methodology, and findings of Principal Component Analysis in equine science.
Characterization of enzootic foci of Venezuelan equine encephalitis virus in western Venezuela. The distribution of the sylvatic subtype ID Venezuelan equine encephalitis (VEE) viruses in the lowland tropical forests of western Venezuela was investigated using remote sensing and geographic information system technologies. Landsat 5 Thematic Mapper satellite imagery was used to study the reflectance patterns of VEE endemic foci and to identify other locations with similar reflectance patterns. Enzootic VEE virus variants isolated during this study are the closest genetic relatives of the epizootic viruses that emerged in western Venezuela during 1992-1993. VEE virus surveillance was condu...
Responses of horses in behavioural tests correlate with temperament assessed by riders. Behavioural tests as well as observers' ratings have been used to study horses' temperament. However, the relationship between the ratings and the responses in behavioural tests has not yet been studied in detail. Objective: The aim of the present study was to examine this relationship between ratings and responses. Methods: Eighteen mature Swedish Warmblood horses were subjected to 2 behavioural tests, one relating to novelty (novel object test) and one to handling (handling test). Subsequently, 16 of these horses were ridden by 16 equally experienced students, having no former experience wit...
Analysis of the variations in clinical signs shown by 254 cases of equine headshaking. A national survey of headshaking in 254 horses was undertaken to describe the clinical signs of the condition as observed by horse owners. Principal component analysis was used to determine the underlying structure of 11 signs and the criteria by which the affected horses could be most effectively differentiated; the analysis suggested five components with a variance greater than one which together explained over 60 per cent of the total variance. Other analyses of the data indicated that headshaking could develop at any age and that twice as many males were affected as females; 64 per cent of...
Locomotor characteristics of horses with navicular disease. To determine whether force-plate evaluation of horses with navicular disease would reveal an abnormal gait that persists despite loss of sensation to the palmar foot region, which may predispose such horses to navicular disease. Methods: 17 clinically normal Thoroughbreds and 8 Thoroughbreds with navicular disease. Methods: Data on ground reaction forces were obtained in trotting horses, using a force plate. Force-time curve variables for clinically normal horses were derived from 4 points at the beginning and 4 points at the end of the vertical and craniocaudal horizontal plots. Principal com...
The genetic structure of Spanish Celtic horse breeds inferred from microsatellite data. Partition of the genetic variability, genetic structure and relationships among seven Spanish Celtic horse breeds were studied using PCR amplification of 13 microsatellites on 481 random individuals. In addition, 60 thoroughbred horses were included. The average observed heterozygosity and the mean number of alleles were higher for the Atlantic horse breeds than for the Balearic Islands breeds. Only eight percentage of the total genetic variability could be attributed to differences among breeds (mean FST approximately 0.08; P < 0.01). Atlantic breeds clearly form a separate cluster from th...
Effect of furosemide on performance of Thoroughbreds racing in the United States and Canada. To determine the effect of furosemide on performance of Thoroughbreds racing on dirt surfaces at tracks in the United States and Canada. Methods: Cross-sectional study. Methods: All Thoroughbreds (n = 22,589) that finished a race on dirt surfaces at tracks in the United States and Canada between June 28 and July 13, 1997 in jurisdictions that allowed the use of furosemide. Methods: Race records were analyzed by use of multivariable ANOVA procedures and logistic regression analyses to determine the effect of furosemide on estimated 6-furlong race time, estimated racing speed, race earnings, and...
Disease-specific changes in equine ground reaction force data documented by use of principal component analysis. To assess the force plate as a diagnostic aid in equine locomotor abnormalities, particularly for abnormalities such as navicular disease that do not have specific diagnostic criteria. Methods: 17 Thoroughbreds without observable locomotor abnormalities (group A), 6 Thoroughbreds with superficial digital flexor tendon injury (group B), and 8 Thoroughbreds with navicular disease (group C). Methods: Using a force plate, ground reaction force patterns were recorded at the trot. Peak limb vertical force and force/time curve parameters were derived from 4 identifiable points at the beginning and en...
[Population genetic parameters of aboriginal Yakut horses as related to modern breeds of the domestic horse Equus caballus L]. This study was the first to analyze the polymorphic characteristics of a wide range of biochemical markers in aboriginal Yakut horses. A total of 124 alleles, including 48 alleles of seven blood-group loci and 76 alleles of ten loci for enzymes and other proteins, were studied. For these polymorphic systems, a computer analysis of the genetic distances between 85 horse breeds of different origin from all parts of the world was performed. The low level of hereditary variation in the Yakut horses confirmed that this breed is old and has long been an isolated population. Phylogenetic analysis dem...
The use of functional indexes to evaluate fitness in Andalusian horses. The fitness of 8 Andalusian horses between 3 and 4 years of age was analysed. The animals were subjected to an exercise test on a sandy track consisting of 2 stages of different intensities. The first stage was of submaximal intensity at 4 speeds which increased progressively (4.17, 5.56, 6.94 and 8.33 m/sec.) covering a distance of 1,000 m in each level. Between each of these speeds, the horses rested for 2 min. The second stage was a maximal speed test over the same distance carried out 2 min after the ending of the maximal phase. Data of heart rate, plasma lactate concentration, velocity, P...
Muscle biopsy as a tool for assessing muscular adaptation to training in horses. To describe an applied method for quantitative estimation of training condition in horses. Methods: 17 sedentary adult (5 to 14 years old) stallions of several breeds endurance trained for 3 months. Methods: Muscle biopsy specimens from 2 depths (20 and 60 mm) of the gluteus medius muscle were obtained before and after training and were analyzed for fiber type distribution, mean cross-sectional area, relative fiber area, and mean number of capillaries in contact with each fiber type relative to their mean area. Fiber types were designated as types 1, 2A, and 2B (high, low, and moderate myosin ...
Muscle biopsy index for discriminating between endurance horses with different performance records. Biopsies were taken from three different depths of the gluteus medius muscle of 36 endurance horses aged between four and 17 years. Twenty of the horses were considered excellent performers according to their three fastest records in endurance events over the previous two or three years. The other 16 horses were moderate performers, with a mean racing speed < 3.5 ms-1 (in 120 to 180 km endurance rides), < 4.0 ms-1 (in 80 to 120 km endurance rides) or < 3.75 ms-1 (in 40 to 60 km endurance rides). The biopsy specimens were analysed for fibre type distribution (type I, IIA and IIB), fibr...
Principal component analysis, using the measurements during running and swimming test, in thoroughbred horses. To investigate whether the running exercise fitness of individual horses could be assessed by a standardized swimming exercise test, the results of multivariate analysis of the exercise parameters measured during incremental running and swimming tests were compared. Ten thoroughbred horses were subjected to different types of exercise tests on a track or in a pool, and the maximum heart rate during and the blood lactate concentration immediately after the exercise were examined. Serial exercise parameters (VLA2, VLA4, LA0, V150, V200, HRS, HRLA2, HRLA4) referred to as the indices related to th...
[Investigations on the individual-region distribution of adipocyte diameters by means of advanced statistical methods]. The dimensional distributions of the adipocytes in Equus caballus in many subjects and in many regions have been studied: such distributions turn out to be in good approximation galtonian ones. Furthermore, all the logarithm populations of the cell diameters have significantly the same variance. The used statistical methods (ANOVA two way with replications, and TUKEY -test) indicate an extremely significant different among the various regions (the smallest cells are in the supra-orbital fossa, the greatest ones are in the abdominal subserous floor).
