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The effects of a shared teacher-child play intervention on the amount and type of targeted play behaviors of young children with blindness were evaluated. Nondirective strategies (following the child's lead to make indirect play suggestions, modeling appropriate play activities, and participating as a play partner) resulted in improved play behaviors by all three children. (Author/DB)

The social participation patterns of 28 young children with visual impairments (some with additional disabilities) during free-play periods was compared across specialized and integrated settings. Although no significant differences were found between settings, there were significant differences between children with and without additional disabilities. (Author/DB)

Sixty-five persons with visual impairments were videotaped as they located and learned the arrangement of five objects in a novel space. Analysis of videotapes and verbal self-reports of the 15 best performing participants revealed that they implemented systematic perimeter and/or gridline patterns, utilized their canes efficiently, and implemented object-link types of search patterns. (JDD)

This article reports the findings of a survey of 37 orientation and mobility specialists who serve preschool-age visually impaired children. It presents demographics of the children and the specialists involved in long cane instruction and identifies the factors related to the decision to begin this instruction. (Author/DB)

Author(s): K. S. Novoselov [1]; A. K. Geim (corresponding author) [1]; S. V. Dubonos [3]; E. W. Hill [2]; I. V. Grigorieva [1] The discrete nature of crystal lattices plays [...]

Summary: Fractures are medical conditions that compromise the athletic potential of horses and/or the safety of jockeys. Therefore, the reduction of fracture risk is an important horse and human welfare issue. The present study used molecular genetic approaches to determine the effect of genetic risk for fracture at four candidate SNPs spanning the myostatin (MSTN) gene on horse chromosome 18. Among the 3706 Japanese Thoroughbred racehorses, 1089 (29.4%) had experienced fractures in their athletic life, indicating the common occurrence of this injury in Thoroughbreds. In the case/control association study, fractures of the carpus (carpal bones and distal radius) were statistically associated with g.65809482T/C (P = 1.17 x 10‐8), g.65868604G/T (P = 2.66 x 10‐9), and g.66493737C/T (P = 6.41 x 10‐8). In the retrospective cohort study using 1710 racehorses born in 2000, the relative risk (RR) was highest for male horses at g.65868604G/T, based on the dominant allele risk model (RR = 2.251, 95% confidence interval 1.407–3.604, P = 0.00041), and for female horses at g.65868604G/T, based on the recessive allele risk model (RR = 2.313, 95% confidence interval 1.380–3.877, P = 0.00163). Considering the association of these SNPs with racing performance traits such as speed, these genotypes may affect the occurrence of carpus fractures in Japanese Thoroughbred racehorses as a consequence of the non‐genetic influence of the genotype on the distance and/or intensity of racing and training. The genetic information presented here may contribute to the development of strategic training programs and racing plans for racehorses that improve their health and welfare. [ABSTRACT FROM AUTHOR]

Obtaining an accurate profile of the spatial sensitivity of Hall cross structures is crucial if such devices are to be used to analyze the switching behavior of magnetic nanostructures and determine the switching field distribution of bit patterned media. Here, we have used the anomalous Hall effect to investigate the switching of patterned Co/Pt multilayer magnetic nanoislands, where the Hall cross has been integrated into the Pt seed layer. Using the anomalous Hall output voltage we have observed the magnetic switching of individual islands, allowing the spatial sensitivity across a Hall cross structure to be determined. The experimental results agree well with numerical simulation studies, using a three-dimensional finite element model, and with existing theoretical studies, where the spatial sensitivity of two-dimensional Hall cross structures have been found numerically. [ABSTRACT FROM AUTHOR]

The influence of the deposition process on the magnetic characteristics of coupled permalloy thin films with thicknesses ranging from 200 to 1,300 angstroms was investigated. The results showed that in the permalloy thickness range of 200-600 angstroms, the coercivity was substantially affected by the substrate temperature. Samples prepared at 40 degrees celsius had lower coercivities than those deposited at 400 degrees celsius.

Summary: Despite strong selection for athletic traits in Thoroughbred horses, there is marked variation in speed and aptitude for racing performance within the breed. Using global positioning system monitoring during exercise training, we measured speed variables and temporal changes in speed with age to derive phenotypes for GWAS. The aim of the study was to test the hypothesis that genetic variation contributes to variation in end‐point physiological traits, in this case galloping speed measured during field exercise tests. Standardisation of field‐measured phenotypes was attempted by assessing horses exercised on the same gallop track and managed under similar conditions by a single trainer. PCA of six key speed indices captured 73.9% of the variation with principal component 1 (PC1). Verifying the utility of the phenotype, we observed that PC1 (median) in 2‐year‐old horses was significantly different among elite, non‐elite and unraced horses (P < 0.001) and the temporal change with age in PC1 varied among horses with different myostatin (MSTN) g.66493737C>T SNP genotypes. A GWAS for PC1 in 2‐year‐old horses (n = 122) identified four SNPs reaching the suggestive threshold for association (P < 4.80 × 10−5), defining a 1.09 Mb candidate region on ECA8 containing the myosin XVIIIB (MYO18B) gene. In a GWAS for temporal change in PC1 with age (n = 168), five SNPs reached the suggestive threshold for association and defined candidate regions on ECA2 and ECA11. Both regions contained genes that are significantly differentially expressed in equine skeletal muscle in response to acute exercise and training stimuli, including MYO18A. As MYO18A plays a regulatory role in the skeletal muscle response to exercise, the identified genomic variation proximal to the myosin family genes may be important for the regulation of the response to exercise and training. [ABSTRACT FROM AUTHOR]

Summary: Background: Race distance aptitude in Thoroughbred horses is highly heritable and is influenced largely by variation at the myostatin gene (MSTN). Objectives: In addition to MSTN, we hypothesised that other modifying loci contribute to best race distance. Study design: Using 3006 Thoroughbreds, including 835 'elite' horses, which were >3 years old, had race records and were sampled from Europe/Middle‐East, Australia/New Zealand, North America and South Africa, we performed genome‐wide association (GWA) tests and separately developed a genomic prediction algorithm to comprehensively catalogue additive genetic variation contributing to best race distance. Methods: 48,896 single‐nucleotide polymorphism (SNP) genotypes were generated from high‐density SNP genotyping arrays. Heritability estimates, tests of GWA and genomic prediction models were derived for the phenotypes: average race distance, best race distance for elite, nonelite and all winning horses. Results: Heritability estimates were high (hm2 = 0.51, best race distance – elite; hm2 = 0.42, best race distance – nonelite; hm2 = 0.40, best race distance – all) and most of the variation was attributed to the MSTN gene. MSTN locus SNPs were the most strongly associated with the trait and included BIEC2‐438999 (ECA18:66913090; P = 4.51 × 10−110, average race distance; P = 2.33 × 10−42, best race distance – elite). The genomic prediction algorithm enabled the inclusion of variation from all SNPs in a model that partitioned horses into short and long cohorts following assignment of MSTN genotype. Additional genes with minor contributions to best race distance were identified. Main limitations: The nongenetic influence of owner/trainer decisions on placement of horses in suitable races could not be controlled. Conclusions: MSTN is the single most important genetic contributor to best race distance in the Thoroughbred. Employment of genetic prediction models will lead to more accurate placing of horses in races that are best suited to their inherited genetic potential for distance aptitude. [ABSTRACT FROM AUTHOR]

Summary: Durability traits in Thoroughbred horses are heritable, economically valuable and may affect horse welfare. The aims of this study were to test the hypotheses that (i) durability traits are heritable and (ii) genetic data may be used to predict a horse's potential to have a racecourse start. Heritability for the phenotype 'number of 2‐ and 3‐year‐old starts' was estimated to be hm2 = 0.11 ± 0.02 (n = 4499). A genome‐wide association study identified SNP contributions to the trait. The neurotrimin (NTM), opioid‐binding protein/cell adhesion molecule like (OPCML) and prolylcarboxypeptidase (PRCP) genes were identified as candidate genes associated with the trait. NTM functions in brain development and has been shown to have been selected during the domestication of the horse. PRCP is an established expression quantitative trait locus involved in the interaction between voluntary exercise and body composition in mice. We hypothesise that variation at these loci contributes to the motivation of the horse to exercise, which may influence its response to the demands of the training and racing environment. A random forest with mixed effects (RFME) model identified a set of SNPs that contributed to 24.7% of the heritable variation in the trait. In an independent validation set (n = 528 horses), the cohort with high genetic potential for a racecourse start had significantly fewer unraced horses (16% unraced) than did low (27% unraced) potential horses and had more favourable race outcomes among those that raced. Therefore, the information from SNPs included in the model may be used to predict horses with a greater chance of a racecourse start. [ABSTRACT FROM AUTHOR]

Summary: The Mongolian horse represents one of the most ancient extant horse populations. In this study we determined the male‐specific region of the Y chromosome (MSY) haplotype distribution in 60 Chinese Mongolian horses representing five distinct populations. Cosmopolitan male lineages were predominant in horses from one improved (Sanhe), one Chinese Mongolian subtype (Baicha Iron Hoof) and one indigenous (Abaga Black) population. In contrast, autochthonous Y chromosome diversity was evident among the two landrace populations (Wushen and Wuzhumuqin), as the majority of their MSY haplotypes were situated at root nodes in a network. Our results also suggest gene flow between Chinese Mongolian and Arabian horses, as an appreciable number of Wuzhumuqin horses carried haplotypes that are typically observed in Arabian horses. Although most horses carried modern haplotypes as a direct result of recent breed improvement, authentic Chinese Mongolian horses retain an ancient signature of paternal lineages that has not previously been described in extant horse populations. Therefore, further characterization of MSY variation in these populations will be important for the discovery of lost diversity in modern domestic horses and also for understanding the evolutionary history of equine paternal lineages. [ABSTRACT FROM AUTHOR]

Summary: Background: We hypothesised that grade/appearance for upper respiratory tract (URT) disorders identified at the first overground endoscopy (OGE) examination would vary at subsequent examinations. Objectives: To compare OGE examinations from horses evaluated on at least two occasions under similar exercise conditions without treatment intervention. Study design: Retrospective cohort. Methods: Pre‐exercise and exercising OGE recordings from Thoroughbred horses undergoing multiple examinations under similar exercise conditions were reviewed, with the first two recordings for each horse statistically evaluated. Paired Wilcoxon signed‐rank tests were used to assess differences in exercise and physiological parameters between examinations. Z‐tests were used to assess the proportion of changes in URT disorder grade/appearance between examinations. A McNemar's test was used to compare the proportion of horses with each disorder at each examination. Test–retest reliability across examinations was assessed using Spearman's ρ, and ordered logistic regression used to explore temporal effects on repeatability. Lattice plots were constructed to view variability in disorders over time. Results: Seventy‐eight horses (median age 2.4 years) with 195 resting endoscopic examinations including 72/78 horses with 179 pre‐exercise and exercising OGE examinations were evaluated. Median time between examinations was 226.5 days with no differences between exercise and physiological parameters. Grades significantly varied between examinations for all disorders, and in particular for palatal instability (PI) and epiglottic grade at rest. A temporal link between examination interval and disorder grade change was identified for PI and resting arytenoid asymmetry. Main limitations: OGE re‐examinations within a shorter, more consistent time‐frame would allow determination of intrahorse variability. The sample size was inadequate to conclusively establish temporal links between disorders and time between examinations. Conclusions: Variability for most URT abnormalities identified with OGE should be considered when making therapeutic decisions based on a single examination and may partially explain development of additional URT conditions after surgical intervention. The Summary is available in Portuguese ‐ see Supporting Information [ABSTRACT FROM AUTHOR]

Summary: Background: Endoscopic tip placement in the pharynx and water flushing interval (FI) may affect exercising upper respiratory tract (URT) endoscopic results. Objectives: To determine associations between the endoscopic tip position in the pharynx and automated FI with overground endoscopic (OGE) results. Study design: Randomised balanced 2X5 factorial design. Methods: A total of n = 200 horses undergoing OGE were randomly assigned into 10 groups (n = 20/group) of different automated endoscopic FIs (no flushing, 60, 120, 180, 240 s) with the endoscope tip positioned either rostrally (position A) or caudally (position B) in the pharynx. Endoscopic videos were analysed and all URT abnormalities graded using published scales. Disorders with ≤10% prevalence were excluded from the final analysis with only arytenoid asymmetry at exercise (AAex), vocal fold collapse (VFC), palatal dysfunction (PD) and medial deviation of the aryepiglottic folds (MDAF) included. The association of endoscope position and FI with URT disorders was assessed using ordinal regression models with P≤0.05 significant. Results: Endoscope tip positioning was significantly associated with PD grading (P = 0.002), with 63/100 horses diagnosed with PD in position A and 45/100 in position B. No other significant direct associations between URT disease and endoscope tip position were identified, although interactions between exercise velocity and endoscope position affected MDAF grade. FI was not directly associated with alterations in disorder grading, although interactions between exercise velocity and FI appeared to affect MDAF grade. Main limitations: The same horse was not evaluated under each test condition potentially resulting in sample bias. Interactions between disorders were not evaluated. The sample size was insufficient to conclusively explore relationships between all factors and disorder grading. Conclusions: Position of the endoscope tip within the pharynx appears to affect grading of PD during OGE examination. Exercise velocity may affect MDAF grade through interactions with endoscope position and FI. [ABSTRACT FROM AUTHOR]

Summary: Background: Conflicting results have been reported for risk factors for recurrent laryngeal neuropathy (RLN) based on resting endoscopic evaluation and comparison of single conformation traits, with many traits correlated to one another. Objectives: To simplify identification of signalment and conformation traits (i.e. variables) associated with RLN cases and controls diagnosed with exercising overground endoscopy (OGE) using exploratory factor analysis (EFA). Study design: Prospective cohort. Methods: Pearson's rank correlation was used to establish significance and association between variables collected from n = 188 Thoroughbreds from one stable by observers blinded to OGE results. Exploratory factor analysis was conducted on nine variables for cases and controls; common elements between variables developed a factor, with variables grouped into three factors for cases and controls respectively. Correlation (loading) between each variable and factor was calculated to rank relationships between variables and cases/controls, with factors retrospectively named based on their underlying correlations with variables. Results: Numerous inter‐correlations were present between variables. Most strongly correlated in cases were wither height with body weight (r = 0.70) and ventral neck length (r = 0.68) and in controls body weight with rostral neck circumference (r = 0.58). Wither height (r = 0.61) significantly loaded the top‐ranked factor for cases ('heightRLN'), explaining 25% of conformational variance. Ventral neck length (r = 0.69) and age (r = 0.57) significantly loaded the second‐ranked factor for cases ('neck lengthRLN'), explaining 16% of conformational variance. Rostral neck circumference (r = 0.86) and body weight (r = 0.6) significantly loaded the top‐ranked factor for controls ('body sizeCON'), explaining 19% of the variance. Wither height (r = 0.84) significantly loaded the second‐ranked factor for controls ('heightCON'), explaining 13% of the variance. Main limitations: Horses had not reached skeletal maturity. Conclusions: Exploratory factor analysis allowed weightings to be determined for each variable. Wither height was the predominant conformational feature associated with RLN. Exploratory factor analysis confirms aggregated conformational differences exist between RLN cases and controls, suitable for future evaluations. [ABSTRACT FROM AUTHOR]

Ninety-nine adolescents with blindness or visual impairments were interviewed about their vocational aims, marriage plans, and recreational activities. Career ambitions included the helping professions, commercial/industrial work, support services, and self-employment; over 50 percent were looking forward to marriage; and favorite hobbies were listening to music, swimming, rock-climbing, and canoeing. (JDD)

E-beam lithography has been used to pattern a continuous Co/Pt multilayer film with perpendicular anisotropy into circular islands of various sizes down to 25 nm diameter on a 60 nm pitch. High resolution magnetic force microscopy with in situ applied field has been used to directly determine the switching field distribution (SFD) and hysteresis loop of the islands. For the smallest islands, the coercivity is reduced and the width of the SFD is increased, indicating that they would not be well suited to data storage applications. [ABSTRACT FROM AUTHOR]

Summary: Adaptation to early training and racing (i.e. precocity), which is highly variable in racing Thoroughbreds, has implications for the selection and training of horses. We hypothesised that precocity in Thoroughbred racehorses is heritable. Age at first sprint training session (work day), age at first race and age at best race were used as phenotypes to quantify precocity. Using high‐density SNP array data, additive SNP heritability ( h SNP 2) was estimated to be 0.17, 0.14 and 0.17 for the three traits respectively. In genome‐wide association studies (GWAS) for age at first race and age at best race, a 1.98‐Mb region on equine chromosome 18 (ECA18) was identified. The most significant association was with the myostatin (MSTN) g.66493737C>T SNP (P = 5.46 × 10−12 and P = 1.89 × 10−14 respectively). In addition, two SNPs on ECA1 (g.37770220G>A and g.37770305T>C) within the first intron of the serotonin receptor gene HTR7 were significantly associated with age at first race and age at best race. Although no significant associations were identified for age at first work day, the MSTN:g.66493737C>T SNP was among the top 20 SNPs in the GWAS (P = 3.98 × 10−5). Here we have identified variants with potential roles in early adaptation to training. Although there was an overlap in genes associated with precocity and distance aptitude (i.e. MSTN), the HTR7 variants were more strongly associated with precocity than with distance. Because HTR7 is closely related to the HTR1A gene, previously implicated in tractability in young Thoroughbreds, this suggests that behavioural traits may influence precocity. [ABSTRACT FROM AUTHOR]

The morphology and stoichiometry of a model iron oxide magnetic tunneling junction heterostructure has been investigated using x-ray photoemission electron microscopy (X-PEEM) and atomic force microscopy (AFM). AFM data evidence islands of width a few μ m and height 10 nm. X-PEEM data show that two types of iron oxide are present, the islands being Fe3O4(111) and the terraces α-Fe2O3(0001). The Fe3O4(111) islands appear as dark areas in X-PEEM, which is attributed to difference in work function and/or mean free path of the two iron oxide phases. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Spin valves are widely used as magnetic microsensors. Their performance is limited by the presence of noise. In this article, signal and noise responses of microfabricated spin valve sensors are investigated in the linear region and in the nonlinear region close to saturation where peaks in noise output have been reported. The anisotropy of the free layer and the pinned layer are in a cross configuration. The noise of the sensor is of 1/f type at low frequency. The signal-to-noise ratio (SNR) as a function of signal frequency was measured near saturation. It is found that below 300 Hz the SNR increases almost linearly as the signal frequency increases. The variation of SNR with excitation current, measured at different frequencies, is shown. The SNR shows a nonlinear characteristic. At low frequency the increase in signal power is matched by that in noise. The SNR curve at 35 Hz shows a maximum as the current increases. The slope of other curves increases with increasing frequency. We explain these curves in a model with thermal excitation. [ABSTRACT FROM AUTHOR]

Polycrystalline Ni[SUB81]Fe[SUB19] films have been vapor-deposited in a forming field onto a 100-μm-thick borosilicate glass. The free surface and film/substrate interface magnetization has been probed using magneto-optical Kerr effect (MOKE) magnetometry, and bulk measurements have been taken using an alternating gradient force magnetometer. Saturation magnetostriction constants were derived from the strain dependence of the anisotropy field in the MOKE measurements, separating out for the first time free surface and interface effects. The free surface showed a clear uniaxial anisotropy with a low dispersion, while the interface showed a mixture of domain switching and moment rotation. We interpret the data in terms of a gradient in magnetic properties through the sample, and discuss consequences for magnetoresistive heads. [ABSTRACT FROM AUTHOR]

Background: Circulating miRNAs (ci-miRNAs) are endogenous, non-coding RNAs emerging as potential diagnostic biomarkers. Equine miRNAs have been previously identified including subsets of tissue-specific miRNAs. In order to investigate ci-miRNAs as diagnostic tools, normal patterns of expression for different scenarios including responses to exercise need to be identified. Human studies have demonstrated that many ci-miRNAs are up-regulated following exercise with changes in expression patterns in skeletal muscle. However, technical challenges such as haemolysis impact on accurate plasma ci-miRNA quantification, with haemolysis often occurring naturally in horses following moderateto- intense exercise. The objectives of this study were to identify plasma ci-miRNA profiles and skeletal muscle miRNAs before and after exercise in Thoroughbreds (Tb), and to evaluate for the presence and effect of haemolysis on plasma ci-miRNA determination. Resting and post-exercise plasma ci-miRNA profiles and haemolysis were evaluated in twenty 3 year-old Tbs in sprint training. Resting and post-exercise skeletal muscle miRNA abundance was evaluated in a second cohort of eleven 2 year-old Tbs just entering sprint training. Haemolysis was further quantified in resting blood samples from twelve Tbs in sprint training. A human plasma panel containing 179 miRNAs was used for profiling, with haemolysis assessed spectrophotometrically. Data was analysed using a paired Student's t-test and Pearson's rank correlation. Results: Plasma ci-miRNA data for 13/20 horses and all skeletal muscle miRNA data passed quality control. From plasma, 52/179 miRNAs were detected at both time-points. Haemolysis levels were greater than the threshold for accurate quantification of ci-miRNAs in 18/25 resting and all post-exercise plasma samples. Positive correlations (P < 0.05) between haemolysis and miRNA abundance were detected for all but 4 miRNAs, so exercise-induced changes in plasma ci-miRNA expression could not be quantified. In skeletal muscle samples, 97/179 miRNAs were detected with 5 miRNAs (miR-21-5p, let-7d-3p, let-7d-5p, miR-30b-5p, miR-30e-5p) differentially expressed (DE, P < 0.05) between time-points. Conclusions: The degree of haemolysis needs to be determined prior to quantifying plasma ci-miRNA expression from horses in high-intensity exercise training. Identification of DE miRNAs in skeletal muscle indicates modification of miRNA expression may contribute to adaptive training responses in Tbs. Using a human plasma panel likely limited detection of equine-specific miRNAs. [ABSTRACT FROM AUTHOR]

Background Previous studies support good intra- and interobserver agreements for endoscopic evaluation of various upper respiratory tract ( URT) diseases in horses. However, these studies mainly assessed resting endoscopic examination videos and/or focussed on a single URT abnormality. Objectives To estimate intra- and interobserver agreement for identification and grading of all URT abnormalities from resting and overground endoscopy ( OGE) videos of Thoroughbreds. Study design Blinded, fully crossed design. Methods Resting and OGE URT videos for n = 43 Thoroughbreds were retrospectively chosen based on identification of common URT disorders. The videos were randomly evaluated in duplicate by 4 raters blinded to all information including prior URT disorder(s) diagnosis. Abnormalities were graded using well-described ordinal scales. Intra- and interobserver agreements were estimated using Cohen's weighted κ and Krippendorff's α, respectively. Results Intraobserver agreement was perfect/nearly perfect for arytenoid symmetry at exercise, epiglottic entrapment and epiglottic retroversion, substantial for arytenoid asymmetry at rest, palatal dysfunction ( PD), medial deviation of the aryepiglottic folds (MDAF), pharyngeal mucus and epiglottic grade at exercise and moderate for vocal fold collapse ( VFC), ventromedial luxation of the apex of the corniculate process of the arytenoid (VLAC), nasopharyngeal collapse ( NPC) and epiglottic grade at rest. Interobserver agreement was substantial for arytenoid symmetry at exercise and PD and moderate for arytenoid asymmetry at rest, MDAF, VLAC and epiglottic entrapment. It was only fair for VFC, epiglottic grade at exercise, epiglottic retroversion, pharyngeal mucus and NPC and poor for epiglottic grade at rest. Main limitations Sample size was insufficient to allow assessment of the effect of one abnormality on the grading of another abnormality. Conclusions Observers were consistent in grading URT disorders. However, significant disparity in grading existed between observers for some conditions affecting reliability. [ABSTRACT FROM AUTHOR]

Presents a study concerning Barkhausen transitions in single layer and bilayer thin permalloy films. Illustration of the coil measurement system; Measurement method used; Results.

Presents a study which examined the role of magnetic dipole coupling in multilayers that typically comprised of ferromagnetic material separated by a nonmagnetic metal spacer. Numerical calculations; Results; Discussion and conclusions.

Presents a study which examined the effects of pinning magnetization with geometrical features in thin permalloy thin film device. Experimental procedure; Numerical predictions; Results.

Presents a study that described a detailed investigation into the magnetic and structural properties of permalloy-tantalum multilayered thin films produced by vacuum evaporation. Use of high-resolution transmission electron microscope; Characteristics of multilayered magnetic thin films; Measurement of the magnetic properties of the thin films.

Presents a study which examined the magnetization distributions in thin film Permalloy strips. Experimental method; Results; Micromagnetic modeling.

Presents an automated vibrating sample magnetometer (VSM) designed to facilitate measurements of the magnetization of conducting samples of different fields and temperatures. Features of the VSM; Description of the coil system used for detecting the magnetic flux of vibrating sample; Schematic diagram of the detection and control system in the VSM.

Reasons for performing study Few noninvasive measures associated with performance assessment are available for racehorse trainers. Evaluation of body composition of superior human sprinters has revealed a lower fat mass ( FM), percentage (%) fat and greater fat-free mass ( FFM), but to date there have been few studies evaluating this in racehorses. Objectives To determine the effects of age, gender and training on body composition and the relationship between body composition, physiological measurements and performance in Thoroughbred racehorses. Methods At 2, 5 and 8 months of training, rump fat thickness ( RFT) was ultrasonographically measured in 1-, 2- and 3-year-old Thoroughbreds (n = 148), with FM, % fat and FFM calculated. Speed, heart rate, plasma lactate and serum creatine kinase concentrations were recorded during each fast work session. Training duration (number of training days) and intensity (number of fast work sessions) were collated for each training period. Retrospective racing performance was used to categorise horses as elite or nonelite. Results FFM was greater in males (P = 0.006) at all training stages. There were no interactions between training duration, intensity, gender and age (P>0.05); all effects were linear. Training duration had a negative effect on RFT (P = 0.0002), FM (P<0.0001) and % fat (P<0.0001) and a positive effect on FFM (P = 0.01). Training intensity had a negative effect on RFT (P = 0.009), FM (P<0.0001), % fat (P<0.0001) and FFM (P<0.0001). FFM was greater for elite vs. nonelite horses at all training stages (P = 0.003), for males (P = 0.05) and females (P = 0.04) and for 2- (P = 0.002) and 3-year-olds (P = 0.02). Conclusions While age and training affect body composition, FFM is associated with performance. Potential relevance Body composition assessment may assist fitness and performance evaluation. [ABSTRACT FROM AUTHOR]

Our multidisciplinary study of historic Thoroughbred horses solves two long-running mysteries in racing history. Eclipse, the greatest racehorse ever known, never lost a race. His skeleton is housed in the Royal Veterinary College, London; however, there is controversy over its authenticity. The 1880 Epsom Derby was won by Bend Or. In one of the great controversies of Thoroughbred racing, the owners of Bend Or were accused of swapping him with another horse, Tadcaster, whose maternal pedigree was more prestigious. Bend Or's skeleton resides at the Natural History Museum, in London. Eclipse and Tadcaster were both extremely popular at stud, and the vast majority of racehorses today are descendents. We compared mitochondrial DNA haplotypes of living and historic Thoroughbred skeletons, including those of Eclipse and Bend Or. Additionally, we compared skeletal morphometrics of Eclipse's skeleton with measurements taken at autopsy. Carbon and nitrogen stable isotopes of a range of skeletal elements were compared in order to establish that the Eclipse skeleton was that of a single horse. Our multidisciplinary data suggest that the putative skeleton is consistent with that of Eclipse. In contrast, mitochondrial DNA haplotype sharing indicated that the skeleton known as Bend Or is most probably that of Tadcaster. [ABSTRACT FROM AUTHOR]

The article discusses results of a study that examines mitochondrial DNA from 1929 horses to determine the origin of Thoroughbred racehorses. The study material and methods are discussed, including polymerase chain reactions and comparison of data with 1550 horse D-loop sequences available from GenBank. The study showed that Thorougbred foundation mares have a cosmopolitan European heritage with influence from British and Irish Native mares.