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Author |
Ridge, J.A.; Baldwin, R.L.; Labhardt, A.M. |
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Title |
Nature of the fast and slow refolding reactions of iron(III) cytochrome c |
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Journal Article |
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Year |
1981 |
Publication |
Biochemistry |
Abbreviated Journal |
Biochemistry |
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Volume |
20 |
Issue  |
6 |
Pages |
1622-1630 |
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Keywords |
Animals; Ascorbic Acid; *Cytochrome c Group; Guanidines; Horses; Kinetics; Oxidation-Reduction; Protein Conformation; Spectrum Analysis |
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Abstract |
The fast and slow refolding reactions of iron(III) cytochrome c (Fe(III) cyt c), previously studied by Ikai et al. (Ikai, A., Fish, W. W., & Tanford, C. (1973) J. Mol. Biol. 73, 165--184), have been reinvestigated. The fast reaction has the major amplitude (78%) and is 100-fold faster than the slow reaction in these conditions (pH 7.2, 25 degrees C, 1.75 M guanidine hydrochloride). We show here that native cyt c is the product formed in the fast reaction as well as in the slow reaction. Two probes have been used to test for formation of native cyt c. absorbance in the 695-nm band and rate of reduction of by L-ascorbate. Different unfolded species (UF, US) give rise to the fast and slow refolding reactions, as shown both by refolding assays at different times after unfolding (“double-jump” experiments) and by the formation of native cyt c in each of the fast and slow refolding reactions. Thus the fast refolding reaction is UF leads to N and the slow refolding reaction is Us leads to N, where N is native cyt c, and there is a US in equilibrium UF equilibrium in unfolded cyt c. The results are consistent with the UF in equilibrium US reaction being proline isomerization, but this has not yet been tested in detail. Folding intermediates have been detected in both reactions. In the UF leads to N reaction, the Soret absorbance change precedes the recovery of the native 695-nm band spectrum, showing that Soret absorbance monitors the formation of a folding intermediate. In the US leads to N reaction an ascorbate-reducible intermediate has been found at an early stage in folding and the Soret absorbance change occurs together with the change at 695 nm as N is formed in the final stage of folding. |
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0006-2960 |
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PMID:6261802 |
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Equine Behaviour @ team @ |
Serial |
3809 |
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Author |
Czerlinski, G.H.; Erickson, J.O.; Theorell, H. |
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Title |
Chemical relaxation studies on the horse liver alcohol dehydrogenase system |
Type |
Journal Article |
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Year |
1979 |
Publication |
Physiological Chemistry and Physics |
Abbreviated Journal |
Physiol Chem Phys |
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Volume |
11 |
Issue |
6 |
Pages |
537-569 |
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Keywords |
Alcohol Oxidoreductases/*metabolism; Animals; Buffers; Electron Transport; Ethanol/metabolism; Horses; Hydrogen-Ion Concentration; Liver/*enzymology; Mathematics; NAD/metabolism; Oscillometry; Osmolar Concentration; Temperature; Time Factors |
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Abstract |
Chemical relaxation studies on the system horse liver alcohol dehydrogenase, nicotinamide adenine dinucleotide, and ethanol were conducted observing fluorescence changes between 400 and 500 nm. Temperature-jump experiments were performed at pH 6.5, 7.0, 8.0, and 9.0; concentration-jump experiments at pH 9.0. The reciprocal of the slowest relaxation time was found to be linearly dependent upon the enzyme concentration for relatively low enzyme concentrations, as predicted earlier. Use of the wide pH-range necessitated expression of the four apparent dissociation constants of the catalytic reaction cycle in terms of pH-independent constants. The system was described in terms of only one (or two) catalysis-linked protons not associated with the electron transfer. Protonic steps in a buffered system are in rapid equilibrium, too fast to be measured with the equipment available. Assuming only two of the four bimolecular reaction steps in the four-step cycle are fast compared to the remaining two, six cases may be considered with six expressions for the reciprocal of the slowest relaxation time. Comparison with the experimental data revealed that the bimolecular reaction steps governing the slowest relaxation time change with pH. Above the effective time resolution of the temperature-lump instrument with fluorescence detection (0.1 msec) only one other relaxation time was detectable and only at pH 9. This relaxation time, found to be independent of the concentration of all reactants within experimental error (r = 10 +/- 5 msec), is most likely due to an interconversion among ternary complexes. |
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0031-9325 |
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PMID:44918 |
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Equine Behaviour @ team @ |
Serial |
3813 |
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Author |
Verheyen, K.; Price, J.; Lanyon, L.; Wood, J. |
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Title |
Exercise distance and speed affect the risk of fracture in racehorses |
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Journal Article |
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Year |
2006 |
Publication |
Bone |
Abbreviated Journal |
Bone |
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Volume |
39 |
Issue |
6 |
Pages |
1322-1330 |
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Keywords |
Animals; Case-Control Studies; Cohort Studies; England; Exertion; Female; Fractures, Bone/etiology/*veterinary; Horse Diseases/*etiology; Horses/*injuries; Male; Physical Conditioning, Animal/adverse effects/methods; Poisson Distribution; Prospective Studies; Regression Analysis; Risk Factors; Running/injuries/physiology |
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Abstract |
In order to gain insight into those training regimens that can minimise the risk of fracture in athletic populations, we conducted a large epidemiological study in racehorses. Thoroughbred racehorses provide a suitable model for studying fracture development and exercise-related risk factors in physically active populations. They represent a homogeneous population, undertaking intensive exercise programmes that are sufficiently heterogeneous to determine those factors that influence injury risk. Daily exercise information was recorded for a cohort of 1178 thoroughbreds that were monitored for up to 2 years. A total of 148 exercise-induced fractures occurred in the study population. Results from a nested case-control study showed a strong interactive effect of exercise distances at different speeds on fracture risk. Horses that exceeded 44 km at canter (< or =14 m/s) and 6 km at gallop (>14 m/s) in a 30-day period were at particularly increased risk of fracture. These distances equate to ca. 7700 bone loading cycles at canter and 880 loading cycles at gallop. Fifty-six fractures occurred in the subset of study horses that were followed since entering training as yearlings, when skeletally immature (n = 335). Cohort analysis of this data set showed that, in previously untrained bones, accumulation of canter exercise increased the risk of fracture (P < or = 0.01), whereas accumulation of high-speed gallop exercise had a protective effect (P < 0.01). However, increasing distances at canter and gallop in short time periods (up to one month) were associated with an increasing fracture risk. All training exercise involves a balance between the risk of fracture inherent in exposure to loading and the beneficial effect that loading has by stimulating bone cells to produce a more robust architecture. Results from our study provide important epidemiological evidence of the effects of physical exercise on bone adaptation and injury risk and can be used to inform the design of safer exercise regimens in physically active populations. |
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Epidemiology Unit, Animal Health Trust, Newmarket, United Kingdom. kverheyen@rvc.ac.uk |
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8756-3282 |
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PMID:16926125 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4030 |
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Author |
Lagarde, J.; Kelso, J.A.S.; Peham, C.; Licka, T. |
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Title |
Coordination dynamics of the horse-rider system |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of Motor Behavior |
Abbreviated Journal |
J Mot Behav |
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Volume |
37 |
Issue |
6 |
Pages |
418-424 |
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Keywords |
Animals; Biomechanics; *Horses; Humans; Professional Competence; Psychomotor Performance/*physiology; *Sports; Time Factors |
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Abstract |
The authors studied the interaction between rider and horse by measuring their ensemble motions in a trot sequence, comparing 1 expert and 1 novice rider. Whereas the novice's movements displayed transient departures from phase synchrony, the expert's motions were continuously phase-matched with those of the horse. The tight ensemble synchrony between the expert and the horse was accompanied by an increase in the temporal regularity of the oscillations of the trunk of the horse. Observed differences between expert and novice riders indicated that phase synchronization is by no means perfect but requires extended practice. Points of contact between horse and rider may haptically convey effective communication between them. |
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Center for Complex Systems and Brain Sciences, Florida Atlantic University, Boca Raton, FL 33431-771, USA. lagarde@ccs.fau.edu |
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0022-2895 |
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PMID:16280312 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4034 |
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Author |
Pearce, G.P.; May-Davis, S.; Greaves, D. |
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Title |
Femoral asymmetry in the Thoroughbred racehorse |
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Journal Article |
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Year |
2005 |
Publication |
Australian Veterinary Journal |
Abbreviated Journal |
Aust Vet J |
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Volume |
83 |
Issue |
6 |
Pages |
367-370 |
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Keywords |
Animals; Cumulative Trauma Disorders/pathology/*veterinary; Femur/*pathology; Horse Diseases/*pathology/physiopathology; Horses; Locomotion; Physical Conditioning, Animal/*physiology |
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Abstract |
OBJECTIVE: To investigate the occurrence of geometrical asymmetries in the macro-architecture of left and right femurs from Thoroughbred racehorses previously used in competitive training and racing in New South Wales, Australia. METHODS: Detailed postmortem measurements were made of 37 characteristics of left and right femurs from eleven Thoroughbred racehorses euthanased for reasons unrelated to the study. Measurements focused on articulating surfaces and sites of attachment of muscles and ligaments known to be associated with hindlimb locomotion. RESULTS: Five measurements were significantly larger in left compared to right femurs (P < 0.05). The regions showing significant differences between left and right limbs were proximal cranial and overhead medio-lateral widths, greater trochanter depth, depth of the fovea in the femoral head and distal inter-epicondylar width. CONCLUSION: The left-right differences in femoral morphology were associated with sites of muscle and ligament attachment known to be involved with hindlimb function in negotiating turns. These differences may be the result of selection pressure for racing performance on curved race tracks and/or adaptations related to asymmetrical loading of the outside hindlimb associated with repeated negotiation of turns on such tracks. |
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Faculty of Rural Management, University of Sydney, Leeds Parade, Orange, New South Wales 2800. gpp28@cam.ac.uk |
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ISSN |
0005-0423 |
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Notes |
PMID:15986917 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
4036 |
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Author |
Wallner, B.; Brem, G.; Muller, M.; Achmann, R. |
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Title |
Fixed nucleotide differences on the Y chromosome indicate clear divergence between Equus przewalskii and Equus caballus |
Type |
Journal Article |
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Year |
2003 |
Publication |
Animal Genetics |
Abbreviated Journal |
Anim Genet |
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Volume |
34 |
Issue |
6 |
Pages |
453-456 |
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Keywords |
Animals; Base Sequence; DNA, Mitochondrial/genetics; Genetic Variation/*genetics; Horses/classification/*genetics; Male; Molecular Sequence Data; Phylogeny; Probability; Species Specificity; Y Chromosome/*genetics |
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Abstract |
The phylogenetic relationship between Equus przewalskii and E. caballus is often a matter of debate. Although these taxa have different chromosome numbers, they do not form monophyletic clades in a phylogenetic tree based on mtDNA sequences. Here we report sequence variation from five newly identified Y chromosome regions of the horse. Two fixed nucleotide differences on the Y chromosome clearly display Przewalski's horse and domestic horse as sister taxa. At both positions the Przewalski's horse haplotype shows the ancestral state, in common with the members of the zebra/ass lineage. We discuss the factors that may have led to the differences in mtDNA and Y-chromosomal observations. |
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Institut fur Tierzucht und Genetik, Veterinarmedizinische Universitat Wien, Veterinarplatz, Wien, Austria. wallner@i122server.vu-wien.ac.at |
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English |
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ISSN |
0268-9146 |
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Notes |
PMID:14687077 |
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no |
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Call Number |
Equine Behaviour @ team @ |
Serial |
5038 |
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Author |
Oakenfull, E.A.; Ryder, O.A. |
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Title |
Mitochondrial control region and 12S rRNA variation in Przewalski's horse (Equus przewalskii) |
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Journal Article |
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Year |
1998 |
Publication |
Animal Genetics |
Abbreviated Journal |
Anim Genet |
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Volume |
29 |
Issue |
6 |
Pages |
456-459 |
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Keywords |
Animals; DNA, Mitochondrial/*genetics; Female; *Genetic Variation; Horses/*genetics; Male; Pedigree; RNA, Ribosomal/*genetics |
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Abstract |
Variation in the control region and the 12S rRNA gene of all surviving mitochondrial lineages of Przewalski's horse was investigated. Variation is low despite the present day population being descended from 13 individuals probably representing animals from three different regions of its range. Phylogenetic comparison of these sequences, with sequences for the domestic horse, does not resolve the ancestral status of either horse. |
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Center for Reproduction of Endangered Species, Zoological Society of San Diego, CA 92112, USA |
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0268-9146 |
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PMID:9883508 |
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no |
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Call Number |
Equine Behaviour @ team @ |
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5040 |
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Author |
Proops, L.; Walton, M.; McComb, K. |
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Title |
The use of human-given cues by domestic horses, Equus caballus, during an object choice task |
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Journal Article |
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Year |
2010 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
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Volume |
79 |
Issue |
6 |
Pages |
1205-1209 |
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Keywords |
domestication; Equus caballus; horse; interspecific communication; marker cue; pointing; social cognition |
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Abstract |
Selection pressures during domestication are thought to lead to an enhanced ability to use human-given cues. Horses fulfil a wide variety of roles for humans and have been domesticated for at least 5000 years but their ability to read human cues has not been widely studied. We tested the ability of 28 horses to attend to human-given cues in an object choice task. We included five different cues: distal sustained pointing, momentary tapping, marker placement, body orientation and gaze (head) alternation. Horses were able to use the pointing and marker placement cues spontaneously but not the tapping, body orientation and gaze alternation cues. The overall pattern of responding suggests that horses may use cues that provide stimulus enhancement at the time of choice and do not have an understanding of the communicative nature of the cues given. As such, their proficiency at this task appears to be inferior to that of domestic dogs, Canis lupus familiaris, but similar to that of domestic goats, Caprus hircus. |
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0003-3472 |
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Equine Behaviour @ team @ |
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5083 |
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Author |
Bartoš, L.; Bartošová, J.; Starostová, L. |
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Title |
Position of the head is not associated with changes in horse vision |
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Journal Article |
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Year |
2008 |
Publication |
Equine Veterinary Journal |
Abbreviated Journal |
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Volume |
40 |
Issue |
6 |
Pages |
599-601 |
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Keywords |
horse; horse vision; head position; pupil rotation |
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Abstract |
It has become accepted that the horse cannot see directly in front when the nose is lowered and must therefore rely on the rider. We tested the hypothesis that this conclusion would be correct only if the horse did not adjust the eyeball horizontal axis to changes of the head position. The results of the present study suggest that it is unlikely that horses have limited vision in relation to their head position when driven by the rider, and that the horse maintains the optimal horizontal eyeball position regardless of head position relative to the ground. |
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Blackwell Publishing Ltd |
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2042-3306 |
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Equine Behaviour @ team @ |
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5679 |
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Author |
Graf, P.; König von Borstel, U.; Gauly, M. |
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Title |
Practical considerations regarding the implementation of a temperament test into horse performance tests: Results of a large-scale test run |
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Journal Article |
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Year |
2014 |
Publication |
Journal of Veterinary Behavior: Clinical Applications and Research |
Abbreviated Journal |
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Volume |
9 |
Issue |
6 |
Pages |
329-340 |
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Keywords |
novel object test; temperament; personality; horse; performance traits; performance tests |
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Abstract |
Abstract Considering the ever-growing demand of various breeding organizations for an objective, inexpensive, reliable, and easily conducted assessment of the behavior of horses, the aim of our study was to implement a novel-object test and a startling test into any kind of breeding performance testing to assess horses' temperament. Additionally, the influence of testing areas (familiar or unfamiliar), riders, and horse factors such as levels of training, breed, and age were of interest. Furthermore, recommendations for the practical implementation concerning the parameters should be given. Therefore, 1,028 horses over a period of 3 years participated in a temperament test consisting of 5 different stimuli. The horses were either ridden (61.8 %) or led by hand (38.2 %) by an unfamiliar professional rider (N = 43) or a familiar rider (N = 20). Live behavioral observations were taken by a trained observer. Overall, horses' scores for reactivity in the present temperament test were distributed over the whole scale, with lower means and higher standard deviations (6.7 ± 2.2-7.6 ± 2.1) than corresponding scores from the conventional personality evaluation in performance tests (7.7 ± 0.8-8.2 ± 0.5; P < 0.01). High correlations (r = 0.3-0.9; P < 0.001) between the scores for reactivity and the other behavioral parameters (emotional expression, activity, time to calm down, rider's aids) show a large influence of these parameters in assessing the horses' temperament. Factors like breed type, sex, and age had significant influences (P < 0.001) on different scores of the temperament test. In most cases, the rider or handler had no influence on the different scores assessed during the temperament test. The training level and the testing modus never had a significant influence on different scores. Only the testing station or location had a small influence on the scores for the stimulus “bridge” in some horses. Based on the results, it could be concluded that an implementation of a temperament tests into performance testing is possible during various types of testing procedure. Especially the assessment of reactivity, emotional expression, interest in the stimulus and rider's aids during and after passing the stimulus, as well as the time to calm down are important parameters for analyzing the horses' personality. |
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1558-7878 |
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Equine Behaviour @ team @ |
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5867 |
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