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The association between performance in show-jumping and personality traits earlier in life
Applied Animal Behaviour Science 82 (2003) 279–295
The association between performance in show-jumping and personality traits earlier in life E.K. Visser a,c,∗ , C.G. Van Reenen a , B. Engel a , M.B.H. Schilder b , A. Barneveld c , H.J. Blokhuis a a
b
Division of Animal Sciences, Institute for Animal Science and Health, P.O. Box 65, NL-8200 AB Lelystad, The Netherlands Department of Animals and Society, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 17, NL-3584 CZ Utrecht, The Netherlands c Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80.163, NL-3508 TD Utrecht, The Netherlands Accepted 17 March 2003
Abstract For a horse to succeed in a show-jumping career, the individual has to possess both excellent physical abilities as well as a suitable personality to perform under challenging conditions. Forty-one Dutch Warmblood horses were used to develop personality tests and correlations between test variables and early training performances in jumping were studied. In behavioural tests, during the first 2 years of the horses’ lives, personality aspects like emotionality, reactivity to human and learning abilities were quantified. At the age of 3, horses were broken and received early training in show-jumping. The inter-relationship between several performance variables measured during this early training phase were studied using principal component analysis (PCA). Variables measured in the different personality tests (novel-object test, handling test, avoidance-learning test and a reward-learning test) showed no correlations, suggesting that these tests all triggered different aspects of a horse’s personality. This study indicates that it is possible to predict a substantial part of the show-jumping performance of an individual horse later in life by personality traits earlier in life. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Personality; Performance; Horses; Prediction; Individual differences; Behavioural tests
∗ Corresponding address. Present address: Research Institute for Animal Husbandry, P.O. Box 2176, NL-8203 AD Lelystad, The Netherlands. Tel.: +31-320-293390; fax: +31-320-241584. E-mail address: [email protected] (E.K. Visser).
0168-1591/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-1591(03)00083-2
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1. Introduction A potential show-jumper requires different characteristics than the first horse for a youngster. Obviously, in both cases, information on the physical abilities and conformation as well as personality traits of the horse are considered in the selection. However, a common mistake made in selecting a horse is placing insufficient emphasis on the personality (Evans et al., 1977). In general, personality can be defined as the propensity of the animal to behave in certain ways in certain situations (Erhardt and Schouten, 2001). Furthermore, it can be speculated that personality comprises several aspects, some of which become apparent under one circumstance, while other aspects are shown under another circumstance. In the last decades, several equine studies have focused on personality traits like emotionality, handling and learning performance (Sommer et al., 1996; Le Scolan et al., 1997; Rundgren and Nordin, 1997; Hausberger et al., 1998; Anderson et al., 1999). In some of these studies, variables of different tests were found to correlate with each other. For example, variables measuring learning capacity were found to correlate with variables assessments of the level of emotionality or ease of handling (Fiske and Potter, 1979; Heird et al., 1981; Heird et al., 1986a; Heird et al., 1986b; Le Scolan et al., 1997). Unfortunately most of these studies have, probably due to the costs of longer studies, only measured aspects of personality at a single moment or within a short time-frame. Additionally, in only a few studies an attempt has been made to relate such aspects of personality to measures (indirectly related to the level) of performance. Performance of the horse is regarded satisfactory when the abilities of the horse, physically as well as mentally, match the considered goal. In the end, the desired performance for a show-jumper will be a high number of competitions won, while the desired performance of a horse for a youngster will be reliability, patience and co-operative behaviour. Trainability for instance, which can be regarded as an indirect measure of performance, has been related to emotionality or learning abilities (Fiske, 1979; Heird et al., 1981; McCall, 1990; Cooper, 1998). Extensive literature has been published in the area of sport performance and personality in humans (e.g. Egloff and Gruhn, 1996). For instance, extroverts are thought to be more venturesome, inclined to take more risks and they are more in pursuit of a competitive situation. Furthermore, athletes are found to be more extroverted compared to non-exercisers. Additionally, anxiety has proven to be negatively related to sport performances due to the interference with the athlete’s concentration on the task (Egloff and Gruhn, 1996). Hence, in humans personality is related to performances in sports. In horses, on the other hand, causes of bad performances are often searched for in clinical disorders (Cator, 1991; Martin et al., 2000; Hernandez and Hawkins, 2001) and much less in personalities. The expectation of good performance is, apart from pedigree, often mainly based on the horse’s conformation. The scope of the present study was two-fold. First, to investigate possible correlations between variables measured in different behavioural tests conducted to quantify personality traits. Secondly, to investigate whether personality traits measured in yearlings are predictive of first performances in show-jumping of the same horses after breaking, at 3 years of age.
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2. Materials and methods All procedures involving animal handling and testing were approved by the Animal Care and Use Committee of the Institute for Animal Science and Health (ID Lelystad) in Lelystad, The Netherlands. 2.1. Animals, housing and management Forty-one Dutch Warmblood horses, born in the spring of 1998, were used in this longitudinal study. At the start of the study 26 colts and 15 fillies were housed in groups of eight or nine horses at the Research Centre for Horse Husbandry in Lelystad, The Netherlands. In summer, horses were at pasture, and in winter in half-open stables (see for more detail, Visser et al., 2001). From 35 months of age horses were housed individually. Between the start of the study and when the horses reached the age of 3, three horses (two geldings, one mare) had to be excluded from the whole study due to health problems. At 37 months of age 38 horses were transported to the National Equestrian Centre (NHB, Deurne, The Netherlands) for a 5-week training programme (see Fig. 1). Horses were simultaneously used in a project aiming at the development of scientific criteria for the selection and the effective and injury free training of show jumpers. To evaluate effects of training at a young age, half of the horses were trained and the other half were not. Training comprised free jumping twice a week and 20 min exercise in a rotary exerciser three times a week. Horses were assigned to one of two treatment groups: trained horses and untrained horses at 5 months of age (see for more detail, Visser et al., 2001).
Fig. 1. Time schedule of personality and performance tests. Personality tests include novel-object test, handling test, avoidance-learning test and reward-learning test all of which took place at the Research Institute for Animal Husbandry in Lelystad. After breaking, horses were transported to the National Equestrian Centre in Deurne where horses were tested for performance. For most of their lives so far horses were housed in groups in stables in winter and on pasture in summer.
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Among the 38 horses that went to the National Equestrian Centre were 18 horses of the former training groups and 20 horses from the untrained group. 2.2. Personality and performance tests Horses were tested repeatedly between 9 and 36 months of age (see Fig. 1). Tests were designed to elicit responses reflecting different aspects of the horses’ personality like temperament, reactivity to humans and learning ability. All tests were performed four times, twice between 9 and 15 months of age, and twice between 21 and 36 months of age. Tests regarding temperament (novel-object test) and reactivity to humans (handling test) were conducted twice within years with an inter-test interval of 1 month. In the novel object, test horses were suddenly confronted with an open white and blue umbrella lowered from the ceiling. In the handling test horses approached a so-called bridge (elevated concrete plates) with a handler; following the approach the horse could decide whether it would follow the handler crossing the bridge or not. Two learning tests, i.e. avoidance learning and reward learning, were also conducted twice within years but with an inter-test interval of 1 day. In the avoidance-learning test horses had to learn to actively avoid compressed puffs of air by crossing a yellow crossbar during the sound of a door bell. In the reward-learning test, horses had to learn to put their nose into one of two food mangers in order to receive a food reward in the other food manger. The exact procedure of the tests is described in Visser et al. (2001): novel object and handling test and in Visser et al. (2003a): learning tests. From the age of 3 all horses were treated alike, i.e. there was no longer a difference made between previously trained and untrained horses. Horses were broken at the Research Station for Horse Husbandry (the ‘Waiboerhoeve’, Lelystad, The Netherlands). This took 4 weeks in total. The first 2 weeks horses were habituated to saddle and bridle with lunging exercise, the second 2 weeks horses were ridden during lunging exercise. The lunging exercise took place, three times a week, 15–20 min at a time. The lunging exercise consisted of equal durations trotting and cantering both sides. After these weeks, horses were, with 9 horses per truckload, transported to the National Equestrian Centre (NHB, Deurne, The Netherlands). At the Equestrian Centre, all 38 horses were assigned to five experienced riders. For the next 5 weeks each rider was coupled with the same seven or eight horses. Horses were ridden 6 days a week. The 5-weeks training schedule consisted of three sessions of free jumping and eight sessions of jumping with the rider. During these training days, jumping performances were evaluated and measured objectively. Apart from the jumping exercises, horses were ridden without jumping exercises the remaining days. Each training session took approximately 20 min, and only two horses were ridden together in the riding hall at all times. Both the free jumping sessions as well as the jumping sessions with riders were carried out following a fixed and well established training schedule for young horses in The Netherlands, in which the height and width of the fences was increased every new training day. The trainer was instructed to train all horses in a standard manner, i.e. not individually. Moreover, the trainer nor the riders knew which horses had received additional training before the age of 36 months and were not informed about the pedigree or any other prior experience with the horse, including results of behavioural tests. During the 5 weeks training at the Equestrian Centre, performance of horses was recorded. Performance was measured during the eight training days and additionally performance was measured when horses
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were ridden in a novel course by unfamiliar riders. The novel course used was similar to the one used in Visser et al. (2003). The novel course included trotting by a novel object in the corner twice, trotting a slalom (twice), showing two correct jumps (50 cm height) and going between two fences (length: 2 m, width: 1.80 m) twice, in this order. The unfamiliar riders, three in total, were students of the National Equestrian Centre (Flyinge, Sweden). Each rider had to ride the course with each horse once. This entailed that all horses had to ride the course three times. To prevent horses for an excessive exercise per day, this performance exercise was spread out over 3 days. Each horse was ridden once per day and each rider rode one third of the horses per day. The rider was instructed to perform all tests in trot. The trainer, though present at the side-line, did not interfere with the riding performance apart from the decision whether a jump or riding between two fences was performed correctly. When horses reared, refused or shied away at the jump or the fence passing, the rider had to approach again until two correct jumps or fence passes were performed, as judged by the trainer. Although some horses refused several times before jumping, at the end all horses completed the novel course. 2.3. Data acquisition In the behavioural tests performed between 9 and 36 months of age, behavioural and physiological variables were measured (see Table 1). Behavioural variables included different forms of locomotion, latency times to approach or touch objects, distance between horse and challenge, vocalisations and postural expressions. The learning performances in the learning tests were also regarded as behavioural variables. Heart rate variables included mean heart rate and a heart rate variability indici, namely root mean square of successive inter-beat differences (RMSSD), see for more detail, Visser et al. (2002).
Table 1 Ages on which tests were conducted and the type of variables measured for the personality and performance tests in horses Test Novel-object test Handling test Avoidance-learning test Reward-learning test First lunging First mounting Transport Training at the NHB Novel course at NHB Final examination at NHB
Age (months)
Behaviour
Heart rate
9, 10, 21, 22 9, 10, 21, 22 14, 30 15, 35 36 36 36 37 37 37
Yesa
Yesb Yesb No/yesc No/yesc Yes Yes No No Yes No
Yesa Yesc Yesc Yes Yes Yes Yes Yes Yes
No/yes indicates that the concerned variable was only measured in the second year. Footnotes refer to the articles in which the results are presented. NHB = National Equestrian Centre in Deurne, The Netherlands. a From Visser et al. (2001). b From Visser et al. (2002). c From Visser et al. (2003a).
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During the first lunging exercises with and without a rider behaviour and heart rate were recorded. Behaviour included different forms of locomotion, position of head and tail, bit acceptance (the horse bending its neck without grasping the bit), vocalisations, head and tail shaking and rearing and bucking. At the day of transport to the Equestrian Centre, the time was recorded that a horse needed to travel from the 10 m line behind the truck until the horse reached the horizontal floor of the truck with both its forelegs. The last 6 m, including the ramp of the truck, were enclosed by straw pellets (height 2 m). During the training sessions at the Equestrian Centre, each attempt to jump was scored as either ‘correct’, ‘touched crossbar’ or ‘crossbar down’. The daily percentage correct jumps was calculated as the number of correct jumps divided by the number of jump attempts. The relative improvement in jumping performance over the 8 days was calculated as the percentage of correct jumps on the eighth day minus the percentage on the first day divided by the percentage on the first day. During the novel course the following behaviours were recorded: refusals, rearing and shying away from objects. Heart rate was recorded during the whole course. Videotaped behaviour was analysed with the Observer® software programme (Noldus Information Technology, Wageningen, The Netherlands). Behavioural variables that were analysed in the personality tests are described in Visser et al. (2001) and Visser et al. (2003a). Heart rate was recorded with Polar® Vantage NV (Polar Electro OY, Kemple, Finland). Heart rate variables used in the personality tests are described in (Visser et al., 2002). All behavioural, heart rate and performance variables analysed in the present paper are summarised in Table 2. 2.4. Definitions In order to prevent confusion, descriptions of several terms will be given below. Firstly, with the learning tests (Visser et al., 2003a) it appeared that horses could be classified as either performer or non-performer in terms of learning abilities. Performers were those horses that completed a daily session of learning trials. Non-performers had to be retired form the learning tests due to non-responding behaviour. To distinguish between these two types of horses and the actual show-jumping performance as 3-year-olds, the performers in the learning test will be referred to as the ‘learning-performers’ in the present paper. Secondly, during the period of time horses were trained at the Equestrian Centre, all horses received jumping training (see Section 2.2). Although horses were ridden 6 days a week, for a total of 5 weeks, their jumping capacities (with rider) were evaluated on 8 days only. The remaining days, horses were also trained but with less emphasis on show-jumping. Therefore, the 8 days the horses’ jumping capacities were evaluated served as performance measures in the present study. These eight evaluation days will be referred to as the eight training days. 2.5. Statistical analysis Earlier findings revealed short-term consistency in tests conducted to quantify aspects of personality (Visser et al., 2001, 2002, 2003a). Therefore, only the variables that were recorded as the first time within a year were used in the analysis of the present paper. Hence, for the first year variables of the novel-object test at 9 months of age, for the
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Table 2 Variables used in the analysis of personality tests and performance test of horses between 9 and 37 months of age (n = 38–41) NO NO NO NO NO NO NO NO NO NO NO NO NO HA HA HA HA HA HA HA HA HA HA HA HA AV AV RE RE BR BR BR BR BR BR TR NHB NHB NHB NHB NHB NHB NHB NHB
Snorting Exploring NO Exploring other Focus NO Head low Latency circle Latency touch NO Trot/canter Tail high ‘Flightiness’ ‘Sensitiveness’ Non-motor HR RMSSD novel Pawing in front Pawing within Attempts crossing Reluctance crossing Restless alone Restless in front Restless within Stand still bridge Walking alone ‘Patience’ ‘Willingness to perform’ RMSSD bridge Correct responses Duration air puffs Perform operant Collect reward Lunging HR Lunging RMSSD Lunging bit Mounting HR Mounting RMSSD Mounting bit Entering Free jumping Jumping rider Refusal novel course Rearing novel course Shying novel course Total duration Heart rate novel course RMSSD novel course
Snorting during exposure to novel objecta Exploring novel object, within one body length of novel objecta Exploring other things in the arenaa Focus (ears and eyes) on novel objecta Head below the imaginary horizontal belly-linea Latency time to enter the circle around the novel objecta Latency time to touch the novel object for the first timea Trotting and cantering during exposure novel objecta Carrying the tail above the imaginary horizontal back linea First PCA component created from nine behavioural variablesa Second PCA component created from nine behavioural variablesa Heart rate corrected for locomotionb Heart rate variability during exposure novel objectb Latency time to first pawing handler in front of boxa Latency time to first pawing handler within boxa Number of attempts per sessiona Reluctance behaviour while approaching the bridgea Restlessness behaviour in box alonea Restlessness behaviour in box handler in fronta Restlessness behaviour in box handler withina Standing still in front of the bridgea Walking in box alonea First PCA component created from nine behavioural variablesa Second PCA component created from nine behavioural variablesa Heart rate variability during approach/crossing bridgea Percentage of correct responses during a sessionc Mean duration of the air puffs given per trialc Latency time to perform the operantc Latency time to collect rewardc Mean heart rate (in bpm) during the test Heart rate variability (in ms) during the test Percentage of time horse accepts the bit Mean heart rate (in bpm) during the test Heart rate variability (in ms) during the test Percentage of time horse accepts the bit Latency time to enter the trailer Average percentage of correct jumps for free jumping during training days Average percentage of correct jumps with rider during training days Number of refusals during first time novel course Number of times rearing during first time novel course Number of times shying away form something during first time novel course Time needed to complete the novel course Mean heart rate (in bpm) relative to baseline recordings Heart rate variability (in ms) during the test relative to baseline recordings
NO: novel-object test, HA: handling test, AV: avoidance-learning test, RE: reward-learning test, BR: breaking, TR: transport, NHB: performances at the National Equestrian Centre. a Detailed description in Visser et al. (2001). b Detailed description in Visser et al. (2002). c Detailed description in Visser et al. (2003a).
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handling test 9 months of age, for the avoidance-learning test 14 months of age and for the reward-learning test 15 months of age. In the second year, variables were used at 10, 10, 30 and 36 months of age, respectively. Tests for main effects of sexes and training and their interactions were based on the common F-test. Spearman rank correlations were calculated between residuals, i.e. variables corrected for sex and training, to study relationships between variables from personality tests and between variables from the personality tests and measurements of show-jumping performance. Principal component analysis (PCA) on residuals was used to construct a new variable for show-jumping performance of 3-year-olds. Multiple stepwise regression was used to search for variables that would significantly predict a substantial part of the variance in show-jumping performance. This analysis was performed twice. Firstly, only with those horses that were classified as performers in the avoidance-learning test (‘learning-performers’), i.e. horses that completed the daily learning session (Visser et al., 2003a). And secondly, with all horses, regardless of their classification in the avoidance-learning test. Classification into a performer or non-performer in the reward-learning test (Visser et al., 2003a) was not included in the analysis since too many horses were classified as non-performer within the first year. Hence, no variables of the reward-learning test were included in the multiple regression. Additionally, multiple regression was also performed with the behavioural variables of the novel-object test and handling test replaced by their principal components as created with a PCA in Visser et al. (2001).
3. Results 3.1. Relation between variables of different personality tests in young horses The heart rate variability measure RMSSD of the novel-object test correlated positively with the RMSSD during the handling test (R2 = 0.41, P < 0.05 first year; R2 = 0.34, P < 0.1 second year). Otherwise, some correlations between variables of different tests approached significance, but none of these were consistent across ages. 3.2. Performance of 3-year-olds Although the trained horses showed more bit acceptance during lunging exercises without rider compared to the untrained horses, this difference was not significant (trained horses: 14.39 ± 6.6% of total time versus untrained horses: 8.66 ± 5.5%). Similarly, bit acceptance during lunging exercise with rider did not differ significantly, between trained and untrained horses (trained horses: 8.80±3.2% versus untrained horses: 3.71±1.4%). The loading of the horses into the truck prior to transport to the training centre took 42.1±10.7 s per horse for the trained horses and 19.1±11.4 s per horse for the untrained horses. This difference was again not significant. The average heart rate while trotting during the first lunging exercise without a rider was 156.4 ±3.4 bpm, with rider 149.4 ±3.7 bpm and while riding the novel course at the Equestrian Centre 130.6 ± 2.3 bpm. The accompanying heart rate variability (RMSSD) were 23.6±3.5, 19.6±3.0 and 25.0±2.3 ms, respectively. There were neither significant differences between trained and untrained horses nor between sexes for the heart rate variables.
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Fig. 2. Percentage of correct jumps with rider for the previously trained (n = 17) and untrained horses (n = 19) during the training days at the National Equestrian Centre in Deurne. 1 = first day jumping with rider, 2 = second day, etc.
At the National Equestrian Centre (NHB, Deurne, The Netherlands), trained horses did not jump significantly better during training days compared to the untrained horses, i.e. there was no significant difference between the percentages of correct jumps with rider (Fig. 2). However, the trained horses had the highest percentage of correct jumps each day. The relative improvement between day 1 and day 8, i.e. the percentage of correct jumps on the eighth day minus the percentage on the first day divided by the percentage on the first day, differed almost significantly between the trained and untrained horses. The trained horses improved on average 5.2% (±9.3%) and the untrained horses improved on average 24.7% (±10.3%) (P = 0.093). Unfortunately, one of the riders from Sweden could not continue her participation in this study after a fall of one of the horses. Another rider replaced her and completed the rides with the remaining horses. The average duration to complete the novel course with the unfamiliar riders was 7.5 min. There were no differences between trained and untrained horses regarding the frequency of refusal, incidence of rearing or times shying. However, the geldings refused significantly more compared to the mares (geldings: 3.9 ± 0.7 times, mares: 1.4 ± 0.6 times, P < 0.05). Five performance variables were used as the input in a PCA (Fig. 3). These performance variables were measured objectively. Four of them, namely ‘shying away’, ‘rearing’, ‘refusal’ and ‘total duration’ were measured during the first time the novel course was ridden with the unfamiliar rider. The fifth, the average percentage of correct jumps during the eight training days, was calculated across the eight days. The first component (PerfC1) accounted for 43.2% of the total variation, the second component for 21.6%. Both components had an eigenvalue of >1, the third component had an eigenvalue of <1. In the present study, the first component (PerfC1) was used as the integrative performance variable for the show-jumping performance of these 3-year-olds. For this performance variable (PerfC1), there appeared to be no significant difference between the trained and untrained horses, nor between sexes.
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Fig. 3. Distribution of behavioural and performance measures in relation to the first two components of a PCA achieved from during a novel course and training days with horses, carried out at 37 months of age (n = 34). Each variable indicates the mean position of this rating score variable in relation to the first two components. Each variable has a specific loading on both the Y and X axes. Corrjumps = average percentage of correct jumps with rider during 8 days training, refusal = number of refusals during the novel course, total duration = time needed to complete the novel course, rearing = number of times horse reared during the novel course, shy = number of times horses shyed away from something during the novel course.
3.3. Relation between personality traits and performance The individual relative improvement, i.e. relative increase in the percentage of correct jumps between day 1 and day 8 of the training period at the Equestrian Centre, did not relate significantly to any variable measured in the personality tests earlier in life. The same applied for the overall average percentage of correct jumps. A multiple regression with variables obtained in the personality tests was conducted to predict the show-jumping performance as a 3-year-old, i.e. first component of the PCA on objective show-jumping performance measures (PerfC1) (see Section 3.2). It appeared that within the ‘learning-performing’ horses 63% of the variance in the show-jumping performance could be explained by variables in personality tests in the first year and 58% in the second year (Table 3). Without distinction between ‘learning-performers’ and ‘learning-non-performers’ in the avoidance-learning test, this percentage was lower. The number of predictors (variables) needed to yield the highest percentage of variance explained ranged from 3 to 6. Several variables of the personality tests, i.e. the novel-object test, the handling test and the avoidance-learning test proved to have a significant contribution to the percentage of variance in show-jumping performance that could be explained with this model. For the ‘learning-performers’, two variables of the novel-object test, namely ‘tail high’ and ‘latency to touch novel object’, contributed significantly in both the first and the second year. The regression coefficients of these variables however, changed from negative
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Table 3 Variables of the personality tests in the first and second year that predict a performance variable in 3-year-old horses, in only performing horses and in all horses regardless performing behaviour in learning tests First year LP % variance explained # predictors # horses Test
Variable
NO NO NO NO NO NO HA HA HA HA AV
RMSSD novel Non-motor HR Focus NO Tail high Trot/canter Latency touch NO Stand still bridge Attempts crossing Reluctance crossing Restlessness within Correct responses
Second year
horsesa
All
63.02 5 22
horsesb
LP horsesa
All horsesb
38.24 4 29
57.96 6 25
36.77 3 28
t-prob
Coeff
t-prob
Coeff
0.004
−0.06
0.132 0.048
−0.03 0.93
0.037
−0.25
0.001 0.261
0.58 −0.37
0.046
0.35
0.132
0.005
0.29
0.86
t-prob
Coeff
0.005 0.301 0.024 0.001
0.55 0.42 −0.41 1.31
0.098 0.008
−0.77 −1.91
t-prob
Coeff
0.147 0.026
0.678 0.390
0.012
0.851
The performance variable is the first component of the PCA on five performance variables (see Fig. 3). % variance explained = percentage of variation in performance that can be explained in the model, # predictors = number of predictors used in the model, t-prob= t-probability, Coeff = regression coefficient, NO = novel-object test, HA = handling test, AV = avoidance-learning test. For explanation of variables, see Table 2. A t-probability of <0.05 is regarded as significant. a Learning performance (LP) horses were those horses that fulfilled the daily session of the avoidance-learning test. b All horses, i.e. performing horses and non-performing horses in avoidance-learning test.
to positive and from positive to negative, respectively. When all horses were considered, different variables in the first and second year contributed significantly (Table 3). Table 4 exhibits the percentage variance of show-jumping performance explained by two heart rate variables of the novel-object test, four components of PCA on behavioural variables of both the novel-object test and the handling test and one variable of the avoidancelearning test. The percentage variance explained is again higher when only the ‘learningperformers’ were considered as compared to all horses. The PCA components of the novel-object test proved to contribute significantly to the percentage of variance explained within the first year when only ‘learning-performers’ were considered (Table 4).
4. Discussion and conclusions 4.1. Relation between different personality traits in young horses The lack of consistent correlations between variables from different personality tests provide basis for the assumption that the novel-object test, the handling test, the reward-learning
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Table 4 Heart rate variables, PCA components of behavioural variables and learning performances of the personality tests in the first and second year that predict the performance variable (PerfC1) in 3-year-old horses, in only performing horses and in all horses regardless performing behaviour in learning tests First year
Second year
LP horsesa % variance explained # predictors # horses Test
Variable
NO NO NO NO HA HA AV
RMSSD novel Non-motor HR PCA C1 ‘flightiness’ PCA C2 ‘sensitiveness’ PCA C1 ‘patience’ PCA C2 ‘willingness to perform’ Correct responses
All horsesb
35.88 5 22
7.75 2 29
t-prob
Coeff
0.012 0.025 0.040 0.197
−0.07 0.29 0.76 −0.21
0.225
0.68
t-prob
0.399 0.457
Coeff
0.29 −0.14
LP horsesa
All horsesb
36.34 4 25
34.28 4 28
t-prob
Coeff
0.275
0.78
0.088
−0.52
0.061 0.289
0.47 −0.77
t-prob
Coeff
0.161
1.18
0.266 0.081
0.14 0.42
0.062
−0.43
The performance variable is the first component (PerfC1) of the PCA on five performance variables (see Fig. 3). % variance explained = percentage of variance in performance that could be explained in the model, # predictors = number of predictors used in the model, t-prob = t-probability, Coeff = regression coefficient, NO = novel-object test, HA = handling test, AV = avoidance-learning test. For explanation of variables, see Table 2. A t-probability of <0.05 is regarded as significant. a Learning performance (LP) horses, were those horses that fulfilled the daily session of the avoidance-learning test. b All horses, i.e. performing horses and non-performing horses in avoidance-learning test.
test and the avoidance-learning test, as conducted in the present study, trigger the individual horse to exhibit different, i.e. no-overlapping, aspects of its personality. Although we possibly succeeded in quantifying several aspects of personality in horses we would like to emphasise that it is likely that these tests do not cover all aspects of the horse’s personality. Depending on the goal for which quantification of personality is desired, different tests, as yet to be developed, might be more powerful. 4.2. Quantifying performance of 3-year-olds Starting point for defining quantitative measures of performance is the optimal definition of performance, given the breeding goal and prospected career of the horses under examination. In the present study, horses were bred and trained to continue in a show-jumping career. Of course, one relevant aspect of performance is the purely technical jumping skill, like the number of correct jumps. But additionally, for a horse to succeed in a jumping career, it should also possess certain qualities of personality that enables it to compete successfully under various challenging conditions. Horses that will shy and rear frequently from new objects or fences, or horses that will easily refuse to jump, are not expected to be winners. Thus, in order to obtain a summary measure of performance, we used a PCA to create a variable that included both technical as well as personality aspects. The first component of
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this PCA (PerfC1) accounted for 43.2% of the variation. The average percentage of correct jumps during eight training days loaded positively on this component, the total duration to complete a novel course and the frequency of refusals and occurrences of rearing loaded all negatively on this component. This component was regarded as the operational measure of performance in the present study. Along the way in reaching the final performance there might yet be another measure, more indirect, related to performance: trainability. In the present study, we measured trainability as the relative improvement over a period of time, i.e. the relative increase in the percentage of correct jumps between day 1 and day 8 of the training period at the Equestrian Centre. Although the slope of the line in Fig. 2 does not immediately suggests any improvement, this is masked by the fact that the height and width of the fences was increased every training day in order to achieve an average percentage of correct jumps of around 80%. Hence, the seemingly relative slightly improvement of 5.2% over the eight training days for the trained horses does not indicate that these horses hardly improved. Despite the daily increases in the height and width of the fences these horses maintained an average of 80–85% correct jumps, therefore they did indeed improve. Furthermore, the results suggest that the untrained horses managed to improve their performance slightly more compared to the trained horses. 4.3. Performance predicted by personality traits The possibility of predicting the performance of horses at an early age already, is favourable for humans and horse. For men it would save a tremendous amount of time and money when investments are made in only those horses that are reliably expected to perform well. For the individual horse, it can be argued that the well-being of the horse during the life-span is optimised when the horse’s abilities, both physically as well as mentally, are matched with its use. Although the physical abilities of jumping horses are of major importance in order to succeed in a show-jumping career, the horses should also possess a certain personality to compete under various challenging conditions. In the present study, attempts were made to predict show-jumping performance, i.e. jumping correctly and not refusing and rearing in a novel course, at the age of 3 by personality as measured in personality tests earlier in life. Differences in putative measures of personality were found to account for up to 63% of the variation in show-jumping performance. When performance was predicted by separate variables, as measured in behavioural tests, the variation that was accounted for appeared to be higher than when principal components of behavioural variables were included in the regression model. Previously (Visser et al., 2001), we assumed that the principal components we derived reflect basic underlying personality traits. The present results show that these personality traits do not represent the best characteristics to predict jumping performance as 3-year-olds. It appeared that when only ‘learning-performers’ of the avoidance-learning test were used in the analysis, the variation in show-jumping performance that was accounted for by personality traits increased compared to when all horses were included. This means that the prediction of show-jumping performance by personality traits was more accurate when only those horses were considered that performed in a learning test. The observation that horses subjected to a learning test could be divided into performers and
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non-performers, i.e. animals that failed to complete the test, has been discussed in detail in a previous paper (Visser et al., 2003a). The relationship between this classification and the prediction of show-jumping performance is intriguing. Few published papers are available documenting the phenomenon that a certain category of animals, labelled as ‘non-learning-performers’ in our work with horses, fail to perform a learning test. Apart from Teskey et al. (1998), who made notice of ‘non-learning-performing’ behaviour in voles tested in a radial maze with eight arms, two equine studies reported that some horses could be classified as non-performers in a learning test (Mader and Price, 1980; Marinier and Alexander, 1994). In these latter studies, it was hypothesised that emotionality represented an important factor associated with ‘non-learning-performing’ in horses. However, this hypothesis was not convincingly supported by results obtained in our own experiment (Visser et al., 2003a). Further analysis revealed that the level of show-jumping performance did not differ between ‘learning-performers’ and ‘non-learning-performers’. We propose two possible explanations underlying the marked differences between the outcomes of regressions with or without ‘non-learning-performing’ horses included in the dataset. Firstly, it might be that in ‘non-learning-performing’ horses, in contrast to ‘leaning performing’ ones, there is no relationship between putative measures of personality and show-jumping performance. Consequently, including ‘non-learning-performers’ in the regression analyses attenuates the quality of fit in comparison with regression analysis without ‘non-learning-performers’. Secondly, the relationship between putative measures of personality and show-jumping performance may be different for ‘non-learning-performing’ horses in comparison with ‘learning-performing’ ones. In this latter case, the prediction of show-jumping performance in ‘non-learning-performing’ horses, based on measures of personality, may be as good as the prediction of show-jumping performance in ‘learning-performing’ horses, but with the use of a different regression model. A tendency towards a significant interaction between being a ‘learning-performer’ or ‘non-learning-performer’ with a co-variable (latency to touch the novel object) on the measure of show-jumping performance points in this direction. However, the present study yielded too few horses, categorised as ‘non-learning-performers’, to investigate this aspect in more detail. Hence, it is stressed that further research on the predictability of performance by personality traits should focus on the possible different relations of performers and non-performers in a learning task with respect to show-jumping performance. Considering the regression for the performers it appeared that three variables, namely ‘tail high’, ‘latency time to touch the novel object’, and ‘standing still in front of the bridge’, that were used as predictors in the first year were also needed in the prediction in the second year. It is commonly believed that the postural tonus, i.e. head and tail carriage, of the horse reflects the horse’s internal state. When evaluating horses’ jumping capacities for instance, only those horses are seriously being evaluated that display a normal postural tonus. Those horses that display a high postural tonus are thought to be too nervous; the high postural tonus prohibits the relaxation of the muscles in the back and hence has a negative influence on the jumping capacities. From a biological point of view, it is commonly believed that a horse elevates its tail when there is an intention movement to move faster. Additionally, the tail is elevated as with investigative approach, approach or avoidance conflict or in frustrations
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conflicts (Kiley-Worthington, 1976). The general assumption that a high tail carriage was caused by nervousness of the horse, is however not supported by the results of the present study. There was no correlation between a heart rate measure generally used for stress assessment (heart rate variability, RMSSD) and ‘tail high’, nor between ‘latency time to touch the novel object’ (a measure putatively related to investigative behaviour) and ‘tail high’. Although the variable ‘tail high’ was included in the regression to predict performance in both the first and the second year, the coefficient signs of this variable was reversed during the second year. ‘Tail high’ contributed negatively to the prediction of show-jumping performance in the first year and positively in the second year. The reason for this inversion in unclear. Also the other two variables, ‘standing still bridge’ and ‘latency to touch the novel object’ showed a reversed phenomenon. It is suggested that the following two things might have contributed to this inversion. Firstly, although the behavioural variables showed excellent individual consistencies within years, between years consistencies were weak (Visser et al., 2001). Hence, it can be speculated that this inversion is caused by the same horses that caused the inconsistency between years. Secondly, it is speculated that the meaning the variables changed during the maturation period. In sum, the present study indicates that it is possible to predict a substantial part of performance by personality traits measured earlier in life. The possible different relation between show-jumping performance for horses failing to perform a learning task needs further investigation. The implication for the horse industry of the present results is that it seems likely that performance can be predicted, at least for a substantial part, by personality traits earlier in life. Yet, further research is needed to investigate the overall picture. Firstly, additional aspects (not personality related variables) should be included in the regression model to predict performance in show-jumping. For instance, the variables related to the development of bone structure or co-ordination. Secondly, the performance in show-jumping, as used in the present study, should only be seen as an indication of future performance. It still has to appear whether the performance of a 3-year-old, as measured here, is comparable to the performance of a 10-year-old in competition. Thirdly, the performance of an animal that is ridden is obviously also dependent on the abilities and personality of the rider. Hence, future research should study the match between horse and rider. Presumably one horse matches better with one rider than with another and hence they will achieve a more satisfying performance. And fourthly, future research could focus on the prediction of other performances (e.g. leisure, dressage, eventing, etc.) but show-jumping by personality aspects. It might be possible that different variables of the same test predict performance other than show-jumping.
Acknowledgements This longitudinal study was enabled by the enthusiastic participation of numerous persons. Firstly, we are grateful to all students that participated in this project: Godelieve Kranendonk, Elisa Kroese, Birgit Brenninkmeijer, Margriet Visch, Femke Schothorst, Dyane van Huisstede, Tine Geurts, Sylvia Oude Veldhuis, Eske Derks, Damay Asjee and Chantal
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Kapteijn. Secondly, we thank the riders of the Equestrian Centres in Sweden (Flyinge) and in The Netherlands (Deurne) for their participation and braveness. Thirdly, we are grateful for the statistical help from the institution, especially to Willem Buist. And fourthly, we wish to thank the employees of the Research station for Animal Husbandry (Lelystad) and the National Equestrian Centre (Deurne) for their hospitality and assistance.
References Anderson, M.K., Friend, T.H., Evans, J.W., Bushong, D.M., 1999. Behavioral assessment of horses in therapeutic riding programs. Appl. Anim. Behav. Sci. 63, 11–24. Cator, R., 1991. Performance evaluations of racing thoroughbreds. J. Equine Vet. Sci. 11, 183–190. Cooper, J.J., 1998. Comparative learning theory and its application in the training of horses. Equine Vet. J. Suppl., 39–43. Egloff, B., Gruhn, A.J., 1996. Personality and endurance sports. Pers. Indiv. Differ. 21, 223–229. Erhardt, H.W., Schouten, W.G.P., 2001. Individual differences and personality. In: Keeling, L., Gonyou, H.W. (Eds.), Social Behaviour in Farm Animals, pp. 333–352. Evans, J.W., Borton, A., Fintz, H.F., VanVleck, L.D., 1977. The Horse. Freeman, San Francisco. Fiske, J.C., 1979. Behavior and learning in horses—applications in management and training. Southwestern Vet. 32, 37–44. Fiske, J.C., Potter, G.D., 1979. Discrimination reversal learning in yearling horses. J. Anim. Sci. 49, 583–588. Hausberger, M., Scolan, N.L., Bruderer, C., 1998. Le temperament du cheval: facteurs en jeu et implications practiques. J. Res. Equine 24, 159–170. Heird, J.C., Lennon, A.M., Bell, R.W., 1981. Effects of early experience on the learning ability of yearling horses. J. Anim. Sci. 53, 1204–1209. Heird, J.C., Lokey, C.E., Cogan, D.C., 1986a. Repeatability and comparison of two maze tests to measure learning ability in horses. Appl. Anim. Behav. Sci. 16, 103–119. Heird, J.C., Whitaker, D.D., Bell, R.W., Ramsey, C.B., Lokey, C.E., 1986b. The effects of handling at different ages on the subsequent learning ability of 2-year-old horses. Appl. Anim. Behav. Sci. 15, 15–25. Hernandez, J., Hawkins, D.L., 2001. Training failure among yearling horses. Am. J. Vet. Res. 62, 1418–1422. Kiley-Worthington, M., 1976. The tail movements of ungulates, canids and felids with particular reference to their causation and function as displays. Behaviour 56, 69–115. Le Scolan, N., Hausberger, M., Wolff, A., 1997. Stability over situations in temperamental traits of horses as revealed by experimental and scoring approaches. Behav. Process. 41, 257–266. Mader, D.R., Price, E.O., 1980. Discrimination learning in horses: effects of breed, age and social dominance. J. Anim. Sci. 50, 962–965. Marinier, S.L., Alexander, A.J., 1994. The use of a maze in testing learning and memory in horses. Appl. Anim. Behav. Sci. 39, 177–182. Martin, B.B., Reef, V.B., Parente, E.J., Sage, A.D., 2000. Causes of poor performance of horses during training, racing, or show-jumping: 384 cases (1992–1996). J. Am. Vet. Med. Assoc. 216, 554–558. McCall, C.A., 1990. A review of learning behavior in horses and its application in horse training. J. Anim. Sci. 68, 75–81. Rundgren, M., Nordin, A., 1997. Personality profile and simple learning tests for horses, Vienna. Sommer, H., Barz, A., Lindner, A., 1996. Testing horses for character and temperament. Tierarztliche Umschau 51, 641–643. Teskey, C.G., Ossenkopp, K.-P., Kavaliers, M., Innis, N.K., Boon, F.H., 1998. Individual differences in radial maze performance and locomotor activity in the meadow vole. Microtus Pennsylvanicus Physiol. Behav. 65, 55–561. Visser, E.K., Van Reenen, C.G., Hopster, H., Schilder, M.B.H., Knaap, J.H., Barneveld, A., Blokhuis, H.J., 2001. Quantifying aspects of young horses’ temperament: consistency of behavioural variables. Appl. Anim. Behav. Sci. 74, 241–258.
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Visser, E.K., Van Reenen, C.G., van der Werf, J.T.N., Schilder, M.B.H., Knaap, J.H., Barneveld, A., Blokhuis, H.J., 2002. Heart rate and heart rate variability during a novel-object test and handling test in young horses. Physiol. Behav. 76, 289–296. Visser, E.K., Van Reenen, C.G., Rundgren, M., Zetterqvist, M., Morgan, K., Blokhuis, H.J., 2003. Responses of horses in behavioural tests correlate with temperament assessed by riders. Equine Vet. J. 35 (2), 176–183. Visser, E.K., Van Reenen, C.G., Schilder, M.B.H., Barneveld, A., Blokhuis, H.J., 2003a. Learning performances in young horses using two different learning tests. Appl. Anim. Behav. Sci. 80, 311–326.
The association between performance in show-jumping and personality traits earlier in life E.K. Visser a,c,∗ , C.G. Van Reenen a , B. Engel a , M.B.H. Schilder b , A. Barneveld c , H.J. Blokhuis a a
b
Division of Animal Sciences, Institute for Animal Science and Health, P.O. Box 65, NL-8200 AB Lelystad, The Netherlands Department of Animals and Society, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 17, NL-3584 CZ Utrecht, The Netherlands c Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80.163, NL-3508 TD Utrecht, The Netherlands Accepted 17 March 2003
Abstract For a horse to succeed in a show-jumping career, the individual has to possess both excellent physical abilities as well as a suitable personality to perform under challenging conditions. Forty-one Dutch Warmblood horses were used to develop personality tests and correlations between test variables and early training performances in jumping were studied. In behavioural tests, during the first 2 years of the horses’ lives, personality aspects like emotionality, reactivity to human and learning abilities were quantified. At the age of 3, horses were broken and received early training in show-jumping. The inter-relationship between several performance variables measured during this early training phase were studied using principal component analysis (PCA). Variables measured in the different personality tests (novel-object test, handling test, avoidance-learning test and a reward-learning test) showed no correlations, suggesting that these tests all triggered different aspects of a horse’s personality. This study indicates that it is possible to predict a substantial part of the show-jumping performance of an individual horse later in life by personality traits earlier in life. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Personality; Performance; Horses; Prediction; Individual differences; Behavioural tests
∗ Corresponding address. Present address: Research Institute for Animal Husbandry, P.O. Box 2176, NL-8203 AD Lelystad, The Netherlands. Tel.: +31-320-293390; fax: +31-320-241584. E-mail address: [email protected] (E.K. Visser).
0168-1591/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-1591(03)00083-2
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1. Introduction A potential show-jumper requires different characteristics than the first horse for a youngster. Obviously, in both cases, information on the physical abilities and conformation as well as personality traits of the horse are considered in the selection. However, a common mistake made in selecting a horse is placing insufficient emphasis on the personality (Evans et al., 1977). In general, personality can be defined as the propensity of the animal to behave in certain ways in certain situations (Erhardt and Schouten, 2001). Furthermore, it can be speculated that personality comprises several aspects, some of which become apparent under one circumstance, while other aspects are shown under another circumstance. In the last decades, several equine studies have focused on personality traits like emotionality, handling and learning performance (Sommer et al., 1996; Le Scolan et al., 1997; Rundgren and Nordin, 1997; Hausberger et al., 1998; Anderson et al., 1999). In some of these studies, variables of different tests were found to correlate with each other. For example, variables measuring learning capacity were found to correlate with variables assessments of the level of emotionality or ease of handling (Fiske and Potter, 1979; Heird et al., 1981; Heird et al., 1986a; Heird et al., 1986b; Le Scolan et al., 1997). Unfortunately most of these studies have, probably due to the costs of longer studies, only measured aspects of personality at a single moment or within a short time-frame. Additionally, in only a few studies an attempt has been made to relate such aspects of personality to measures (indirectly related to the level) of performance. Performance of the horse is regarded satisfactory when the abilities of the horse, physically as well as mentally, match the considered goal. In the end, the desired performance for a show-jumper will be a high number of competitions won, while the desired performance of a horse for a youngster will be reliability, patience and co-operative behaviour. Trainability for instance, which can be regarded as an indirect measure of performance, has been related to emotionality or learning abilities (Fiske, 1979; Heird et al., 1981; McCall, 1990; Cooper, 1998). Extensive literature has been published in the area of sport performance and personality in humans (e.g. Egloff and Gruhn, 1996). For instance, extroverts are thought to be more venturesome, inclined to take more risks and they are more in pursuit of a competitive situation. Furthermore, athletes are found to be more extroverted compared to non-exercisers. Additionally, anxiety has proven to be negatively related to sport performances due to the interference with the athlete’s concentration on the task (Egloff and Gruhn, 1996). Hence, in humans personality is related to performances in sports. In horses, on the other hand, causes of bad performances are often searched for in clinical disorders (Cator, 1991; Martin et al., 2000; Hernandez and Hawkins, 2001) and much less in personalities. The expectation of good performance is, apart from pedigree, often mainly based on the horse’s conformation. The scope of the present study was two-fold. First, to investigate possible correlations between variables measured in different behavioural tests conducted to quantify personality traits. Secondly, to investigate whether personality traits measured in yearlings are predictive of first performances in show-jumping of the same horses after breaking, at 3 years of age.
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2. Materials and methods All procedures involving animal handling and testing were approved by the Animal Care and Use Committee of the Institute for Animal Science and Health (ID Lelystad) in Lelystad, The Netherlands. 2.1. Animals, housing and management Forty-one Dutch Warmblood horses, born in the spring of 1998, were used in this longitudinal study. At the start of the study 26 colts and 15 fillies were housed in groups of eight or nine horses at the Research Centre for Horse Husbandry in Lelystad, The Netherlands. In summer, horses were at pasture, and in winter in half-open stables (see for more detail, Visser et al., 2001). From 35 months of age horses were housed individually. Between the start of the study and when the horses reached the age of 3, three horses (two geldings, one mare) had to be excluded from the whole study due to health problems. At 37 months of age 38 horses were transported to the National Equestrian Centre (NHB, Deurne, The Netherlands) for a 5-week training programme (see Fig. 1). Horses were simultaneously used in a project aiming at the development of scientific criteria for the selection and the effective and injury free training of show jumpers. To evaluate effects of training at a young age, half of the horses were trained and the other half were not. Training comprised free jumping twice a week and 20 min exercise in a rotary exerciser three times a week. Horses were assigned to one of two treatment groups: trained horses and untrained horses at 5 months of age (see for more detail, Visser et al., 2001).
Fig. 1. Time schedule of personality and performance tests. Personality tests include novel-object test, handling test, avoidance-learning test and reward-learning test all of which took place at the Research Institute for Animal Husbandry in Lelystad. After breaking, horses were transported to the National Equestrian Centre in Deurne where horses were tested for performance. For most of their lives so far horses were housed in groups in stables in winter and on pasture in summer.
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Among the 38 horses that went to the National Equestrian Centre were 18 horses of the former training groups and 20 horses from the untrained group. 2.2. Personality and performance tests Horses were tested repeatedly between 9 and 36 months of age (see Fig. 1). Tests were designed to elicit responses reflecting different aspects of the horses’ personality like temperament, reactivity to humans and learning ability. All tests were performed four times, twice between 9 and 15 months of age, and twice between 21 and 36 months of age. Tests regarding temperament (novel-object test) and reactivity to humans (handling test) were conducted twice within years with an inter-test interval of 1 month. In the novel object, test horses were suddenly confronted with an open white and blue umbrella lowered from the ceiling. In the handling test horses approached a so-called bridge (elevated concrete plates) with a handler; following the approach the horse could decide whether it would follow the handler crossing the bridge or not. Two learning tests, i.e. avoidance learning and reward learning, were also conducted twice within years but with an inter-test interval of 1 day. In the avoidance-learning test horses had to learn to actively avoid compressed puffs of air by crossing a yellow crossbar during the sound of a door bell. In the reward-learning test, horses had to learn to put their nose into one of two food mangers in order to receive a food reward in the other food manger. The exact procedure of the tests is described in Visser et al. (2001): novel object and handling test and in Visser et al. (2003a): learning tests. From the age of 3 all horses were treated alike, i.e. there was no longer a difference made between previously trained and untrained horses. Horses were broken at the Research Station for Horse Husbandry (the ‘Waiboerhoeve’, Lelystad, The Netherlands). This took 4 weeks in total. The first 2 weeks horses were habituated to saddle and bridle with lunging exercise, the second 2 weeks horses were ridden during lunging exercise. The lunging exercise took place, three times a week, 15–20 min at a time. The lunging exercise consisted of equal durations trotting and cantering both sides. After these weeks, horses were, with 9 horses per truckload, transported to the National Equestrian Centre (NHB, Deurne, The Netherlands). At the Equestrian Centre, all 38 horses were assigned to five experienced riders. For the next 5 weeks each rider was coupled with the same seven or eight horses. Horses were ridden 6 days a week. The 5-weeks training schedule consisted of three sessions of free jumping and eight sessions of jumping with the rider. During these training days, jumping performances were evaluated and measured objectively. Apart from the jumping exercises, horses were ridden without jumping exercises the remaining days. Each training session took approximately 20 min, and only two horses were ridden together in the riding hall at all times. Both the free jumping sessions as well as the jumping sessions with riders were carried out following a fixed and well established training schedule for young horses in The Netherlands, in which the height and width of the fences was increased every new training day. The trainer was instructed to train all horses in a standard manner, i.e. not individually. Moreover, the trainer nor the riders knew which horses had received additional training before the age of 36 months and were not informed about the pedigree or any other prior experience with the horse, including results of behavioural tests. During the 5 weeks training at the Equestrian Centre, performance of horses was recorded. Performance was measured during the eight training days and additionally performance was measured when horses
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were ridden in a novel course by unfamiliar riders. The novel course used was similar to the one used in Visser et al. (2003). The novel course included trotting by a novel object in the corner twice, trotting a slalom (twice), showing two correct jumps (50 cm height) and going between two fences (length: 2 m, width: 1.80 m) twice, in this order. The unfamiliar riders, three in total, were students of the National Equestrian Centre (Flyinge, Sweden). Each rider had to ride the course with each horse once. This entailed that all horses had to ride the course three times. To prevent horses for an excessive exercise per day, this performance exercise was spread out over 3 days. Each horse was ridden once per day and each rider rode one third of the horses per day. The rider was instructed to perform all tests in trot. The trainer, though present at the side-line, did not interfere with the riding performance apart from the decision whether a jump or riding between two fences was performed correctly. When horses reared, refused or shied away at the jump or the fence passing, the rider had to approach again until two correct jumps or fence passes were performed, as judged by the trainer. Although some horses refused several times before jumping, at the end all horses completed the novel course. 2.3. Data acquisition In the behavioural tests performed between 9 and 36 months of age, behavioural and physiological variables were measured (see Table 1). Behavioural variables included different forms of locomotion, latency times to approach or touch objects, distance between horse and challenge, vocalisations and postural expressions. The learning performances in the learning tests were also regarded as behavioural variables. Heart rate variables included mean heart rate and a heart rate variability indici, namely root mean square of successive inter-beat differences (RMSSD), see for more detail, Visser et al. (2002).
Table 1 Ages on which tests were conducted and the type of variables measured for the personality and performance tests in horses Test Novel-object test Handling test Avoidance-learning test Reward-learning test First lunging First mounting Transport Training at the NHB Novel course at NHB Final examination at NHB
Age (months)
Behaviour
Heart rate
9, 10, 21, 22 9, 10, 21, 22 14, 30 15, 35 36 36 36 37 37 37
Yesa
Yesb Yesb No/yesc No/yesc Yes Yes No No Yes No
Yesa Yesc Yesc Yes Yes Yes Yes Yes Yes
No/yes indicates that the concerned variable was only measured in the second year. Footnotes refer to the articles in which the results are presented. NHB = National Equestrian Centre in Deurne, The Netherlands. a From Visser et al. (2001). b From Visser et al. (2002). c From Visser et al. (2003a).
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During the first lunging exercises with and without a rider behaviour and heart rate were recorded. Behaviour included different forms of locomotion, position of head and tail, bit acceptance (the horse bending its neck without grasping the bit), vocalisations, head and tail shaking and rearing and bucking. At the day of transport to the Equestrian Centre, the time was recorded that a horse needed to travel from the 10 m line behind the truck until the horse reached the horizontal floor of the truck with both its forelegs. The last 6 m, including the ramp of the truck, were enclosed by straw pellets (height 2 m). During the training sessions at the Equestrian Centre, each attempt to jump was scored as either ‘correct’, ‘touched crossbar’ or ‘crossbar down’. The daily percentage correct jumps was calculated as the number of correct jumps divided by the number of jump attempts. The relative improvement in jumping performance over the 8 days was calculated as the percentage of correct jumps on the eighth day minus the percentage on the first day divided by the percentage on the first day. During the novel course the following behaviours were recorded: refusals, rearing and shying away from objects. Heart rate was recorded during the whole course. Videotaped behaviour was analysed with the Observer® software programme (Noldus Information Technology, Wageningen, The Netherlands). Behavioural variables that were analysed in the personality tests are described in Visser et al. (2001) and Visser et al. (2003a). Heart rate was recorded with Polar® Vantage NV (Polar Electro OY, Kemple, Finland). Heart rate variables used in the personality tests are described in (Visser et al., 2002). All behavioural, heart rate and performance variables analysed in the present paper are summarised in Table 2. 2.4. Definitions In order to prevent confusion, descriptions of several terms will be given below. Firstly, with the learning tests (Visser et al., 2003a) it appeared that horses could be classified as either performer or non-performer in terms of learning abilities. Performers were those horses that completed a daily session of learning trials. Non-performers had to be retired form the learning tests due to non-responding behaviour. To distinguish between these two types of horses and the actual show-jumping performance as 3-year-olds, the performers in the learning test will be referred to as the ‘learning-performers’ in the present paper. Secondly, during the period of time horses were trained at the Equestrian Centre, all horses received jumping training (see Section 2.2). Although horses were ridden 6 days a week, for a total of 5 weeks, their jumping capacities (with rider) were evaluated on 8 days only. The remaining days, horses were also trained but with less emphasis on show-jumping. Therefore, the 8 days the horses’ jumping capacities were evaluated served as performance measures in the present study. These eight evaluation days will be referred to as the eight training days. 2.5. Statistical analysis Earlier findings revealed short-term consistency in tests conducted to quantify aspects of personality (Visser et al., 2001, 2002, 2003a). Therefore, only the variables that were recorded as the first time within a year were used in the analysis of the present paper. Hence, for the first year variables of the novel-object test at 9 months of age, for the
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Table 2 Variables used in the analysis of personality tests and performance test of horses between 9 and 37 months of age (n = 38–41) NO NO NO NO NO NO NO NO NO NO NO NO NO HA HA HA HA HA HA HA HA HA HA HA HA AV AV RE RE BR BR BR BR BR BR TR NHB NHB NHB NHB NHB NHB NHB NHB
Snorting Exploring NO Exploring other Focus NO Head low Latency circle Latency touch NO Trot/canter Tail high ‘Flightiness’ ‘Sensitiveness’ Non-motor HR RMSSD novel Pawing in front Pawing within Attempts crossing Reluctance crossing Restless alone Restless in front Restless within Stand still bridge Walking alone ‘Patience’ ‘Willingness to perform’ RMSSD bridge Correct responses Duration air puffs Perform operant Collect reward Lunging HR Lunging RMSSD Lunging bit Mounting HR Mounting RMSSD Mounting bit Entering Free jumping Jumping rider Refusal novel course Rearing novel course Shying novel course Total duration Heart rate novel course RMSSD novel course
Snorting during exposure to novel objecta Exploring novel object, within one body length of novel objecta Exploring other things in the arenaa Focus (ears and eyes) on novel objecta Head below the imaginary horizontal belly-linea Latency time to enter the circle around the novel objecta Latency time to touch the novel object for the first timea Trotting and cantering during exposure novel objecta Carrying the tail above the imaginary horizontal back linea First PCA component created from nine behavioural variablesa Second PCA component created from nine behavioural variablesa Heart rate corrected for locomotionb Heart rate variability during exposure novel objectb Latency time to first pawing handler in front of boxa Latency time to first pawing handler within boxa Number of attempts per sessiona Reluctance behaviour while approaching the bridgea Restlessness behaviour in box alonea Restlessness behaviour in box handler in fronta Restlessness behaviour in box handler withina Standing still in front of the bridgea Walking in box alonea First PCA component created from nine behavioural variablesa Second PCA component created from nine behavioural variablesa Heart rate variability during approach/crossing bridgea Percentage of correct responses during a sessionc Mean duration of the air puffs given per trialc Latency time to perform the operantc Latency time to collect rewardc Mean heart rate (in bpm) during the test Heart rate variability (in ms) during the test Percentage of time horse accepts the bit Mean heart rate (in bpm) during the test Heart rate variability (in ms) during the test Percentage of time horse accepts the bit Latency time to enter the trailer Average percentage of correct jumps for free jumping during training days Average percentage of correct jumps with rider during training days Number of refusals during first time novel course Number of times rearing during first time novel course Number of times shying away form something during first time novel course Time needed to complete the novel course Mean heart rate (in bpm) relative to baseline recordings Heart rate variability (in ms) during the test relative to baseline recordings
NO: novel-object test, HA: handling test, AV: avoidance-learning test, RE: reward-learning test, BR: breaking, TR: transport, NHB: performances at the National Equestrian Centre. a Detailed description in Visser et al. (2001). b Detailed description in Visser et al. (2002). c Detailed description in Visser et al. (2003a).
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handling test 9 months of age, for the avoidance-learning test 14 months of age and for the reward-learning test 15 months of age. In the second year, variables were used at 10, 10, 30 and 36 months of age, respectively. Tests for main effects of sexes and training and their interactions were based on the common F-test. Spearman rank correlations were calculated between residuals, i.e. variables corrected for sex and training, to study relationships between variables from personality tests and between variables from the personality tests and measurements of show-jumping performance. Principal component analysis (PCA) on residuals was used to construct a new variable for show-jumping performance of 3-year-olds. Multiple stepwise regression was used to search for variables that would significantly predict a substantial part of the variance in show-jumping performance. This analysis was performed twice. Firstly, only with those horses that were classified as performers in the avoidance-learning test (‘learning-performers’), i.e. horses that completed the daily learning session (Visser et al., 2003a). And secondly, with all horses, regardless of their classification in the avoidance-learning test. Classification into a performer or non-performer in the reward-learning test (Visser et al., 2003a) was not included in the analysis since too many horses were classified as non-performer within the first year. Hence, no variables of the reward-learning test were included in the multiple regression. Additionally, multiple regression was also performed with the behavioural variables of the novel-object test and handling test replaced by their principal components as created with a PCA in Visser et al. (2001).
3. Results 3.1. Relation between variables of different personality tests in young horses The heart rate variability measure RMSSD of the novel-object test correlated positively with the RMSSD during the handling test (R2 = 0.41, P < 0.05 first year; R2 = 0.34, P < 0.1 second year). Otherwise, some correlations between variables of different tests approached significance, but none of these were consistent across ages. 3.2. Performance of 3-year-olds Although the trained horses showed more bit acceptance during lunging exercises without rider compared to the untrained horses, this difference was not significant (trained horses: 14.39 ± 6.6% of total time versus untrained horses: 8.66 ± 5.5%). Similarly, bit acceptance during lunging exercise with rider did not differ significantly, between trained and untrained horses (trained horses: 8.80±3.2% versus untrained horses: 3.71±1.4%). The loading of the horses into the truck prior to transport to the training centre took 42.1±10.7 s per horse for the trained horses and 19.1±11.4 s per horse for the untrained horses. This difference was again not significant. The average heart rate while trotting during the first lunging exercise without a rider was 156.4 ±3.4 bpm, with rider 149.4 ±3.7 bpm and while riding the novel course at the Equestrian Centre 130.6 ± 2.3 bpm. The accompanying heart rate variability (RMSSD) were 23.6±3.5, 19.6±3.0 and 25.0±2.3 ms, respectively. There were neither significant differences between trained and untrained horses nor between sexes for the heart rate variables.
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Fig. 2. Percentage of correct jumps with rider for the previously trained (n = 17) and untrained horses (n = 19) during the training days at the National Equestrian Centre in Deurne. 1 = first day jumping with rider, 2 = second day, etc.
At the National Equestrian Centre (NHB, Deurne, The Netherlands), trained horses did not jump significantly better during training days compared to the untrained horses, i.e. there was no significant difference between the percentages of correct jumps with rider (Fig. 2). However, the trained horses had the highest percentage of correct jumps each day. The relative improvement between day 1 and day 8, i.e. the percentage of correct jumps on the eighth day minus the percentage on the first day divided by the percentage on the first day, differed almost significantly between the trained and untrained horses. The trained horses improved on average 5.2% (±9.3%) and the untrained horses improved on average 24.7% (±10.3%) (P = 0.093). Unfortunately, one of the riders from Sweden could not continue her participation in this study after a fall of one of the horses. Another rider replaced her and completed the rides with the remaining horses. The average duration to complete the novel course with the unfamiliar riders was 7.5 min. There were no differences between trained and untrained horses regarding the frequency of refusal, incidence of rearing or times shying. However, the geldings refused significantly more compared to the mares (geldings: 3.9 ± 0.7 times, mares: 1.4 ± 0.6 times, P < 0.05). Five performance variables were used as the input in a PCA (Fig. 3). These performance variables were measured objectively. Four of them, namely ‘shying away’, ‘rearing’, ‘refusal’ and ‘total duration’ were measured during the first time the novel course was ridden with the unfamiliar rider. The fifth, the average percentage of correct jumps during the eight training days, was calculated across the eight days. The first component (PerfC1) accounted for 43.2% of the total variation, the second component for 21.6%. Both components had an eigenvalue of >1, the third component had an eigenvalue of <1. In the present study, the first component (PerfC1) was used as the integrative performance variable for the show-jumping performance of these 3-year-olds. For this performance variable (PerfC1), there appeared to be no significant difference between the trained and untrained horses, nor between sexes.
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Fig. 3. Distribution of behavioural and performance measures in relation to the first two components of a PCA achieved from during a novel course and training days with horses, carried out at 37 months of age (n = 34). Each variable indicates the mean position of this rating score variable in relation to the first two components. Each variable has a specific loading on both the Y and X axes. Corrjumps = average percentage of correct jumps with rider during 8 days training, refusal = number of refusals during the novel course, total duration = time needed to complete the novel course, rearing = number of times horse reared during the novel course, shy = number of times horses shyed away from something during the novel course.
3.3. Relation between personality traits and performance The individual relative improvement, i.e. relative increase in the percentage of correct jumps between day 1 and day 8 of the training period at the Equestrian Centre, did not relate significantly to any variable measured in the personality tests earlier in life. The same applied for the overall average percentage of correct jumps. A multiple regression with variables obtained in the personality tests was conducted to predict the show-jumping performance as a 3-year-old, i.e. first component of the PCA on objective show-jumping performance measures (PerfC1) (see Section 3.2). It appeared that within the ‘learning-performing’ horses 63% of the variance in the show-jumping performance could be explained by variables in personality tests in the first year and 58% in the second year (Table 3). Without distinction between ‘learning-performers’ and ‘learning-non-performers’ in the avoidance-learning test, this percentage was lower. The number of predictors (variables) needed to yield the highest percentage of variance explained ranged from 3 to 6. Several variables of the personality tests, i.e. the novel-object test, the handling test and the avoidance-learning test proved to have a significant contribution to the percentage of variance in show-jumping performance that could be explained with this model. For the ‘learning-performers’, two variables of the novel-object test, namely ‘tail high’ and ‘latency to touch novel object’, contributed significantly in both the first and the second year. The regression coefficients of these variables however, changed from negative
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Table 3 Variables of the personality tests in the first and second year that predict a performance variable in 3-year-old horses, in only performing horses and in all horses regardless performing behaviour in learning tests First year LP % variance explained # predictors # horses Test
Variable
NO NO NO NO NO NO HA HA HA HA AV
RMSSD novel Non-motor HR Focus NO Tail high Trot/canter Latency touch NO Stand still bridge Attempts crossing Reluctance crossing Restlessness within Correct responses
Second year
horsesa
All
63.02 5 22
horsesb
LP horsesa
All horsesb
38.24 4 29
57.96 6 25
36.77 3 28
t-prob
Coeff
t-prob
Coeff
0.004
−0.06
0.132 0.048
−0.03 0.93
0.037
−0.25
0.001 0.261
0.58 −0.37
0.046
0.35
0.132
0.005
0.29
0.86
t-prob
Coeff
0.005 0.301 0.024 0.001
0.55 0.42 −0.41 1.31
0.098 0.008
−0.77 −1.91
t-prob
Coeff
0.147 0.026
0.678 0.390
0.012
0.851
The performance variable is the first component of the PCA on five performance variables (see Fig. 3). % variance explained = percentage of variation in performance that can be explained in the model, # predictors = number of predictors used in the model, t-prob= t-probability, Coeff = regression coefficient, NO = novel-object test, HA = handling test, AV = avoidance-learning test. For explanation of variables, see Table 2. A t-probability of <0.05 is regarded as significant. a Learning performance (LP) horses were those horses that fulfilled the daily session of the avoidance-learning test. b All horses, i.e. performing horses and non-performing horses in avoidance-learning test.
to positive and from positive to negative, respectively. When all horses were considered, different variables in the first and second year contributed significantly (Table 3). Table 4 exhibits the percentage variance of show-jumping performance explained by two heart rate variables of the novel-object test, four components of PCA on behavioural variables of both the novel-object test and the handling test and one variable of the avoidancelearning test. The percentage variance explained is again higher when only the ‘learningperformers’ were considered as compared to all horses. The PCA components of the novel-object test proved to contribute significantly to the percentage of variance explained within the first year when only ‘learning-performers’ were considered (Table 4).
4. Discussion and conclusions 4.1. Relation between different personality traits in young horses The lack of consistent correlations between variables from different personality tests provide basis for the assumption that the novel-object test, the handling test, the reward-learning
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Table 4 Heart rate variables, PCA components of behavioural variables and learning performances of the personality tests in the first and second year that predict the performance variable (PerfC1) in 3-year-old horses, in only performing horses and in all horses regardless performing behaviour in learning tests First year
Second year
LP horsesa % variance explained # predictors # horses Test
Variable
NO NO NO NO HA HA AV
RMSSD novel Non-motor HR PCA C1 ‘flightiness’ PCA C2 ‘sensitiveness’ PCA C1 ‘patience’ PCA C2 ‘willingness to perform’ Correct responses
All horsesb
35.88 5 22
7.75 2 29
t-prob
Coeff
0.012 0.025 0.040 0.197
−0.07 0.29 0.76 −0.21
0.225
0.68
t-prob
0.399 0.457
Coeff
0.29 −0.14
LP horsesa
All horsesb
36.34 4 25
34.28 4 28
t-prob
Coeff
0.275
0.78
0.088
−0.52
0.061 0.289
0.47 −0.77
t-prob
Coeff
0.161
1.18
0.266 0.081
0.14 0.42
0.062
−0.43
The performance variable is the first component (PerfC1) of the PCA on five performance variables (see Fig. 3). % variance explained = percentage of variance in performance that could be explained in the model, # predictors = number of predictors used in the model, t-prob = t-probability, Coeff = regression coefficient, NO = novel-object test, HA = handling test, AV = avoidance-learning test. For explanation of variables, see Table 2. A t-probability of <0.05 is regarded as significant. a Learning performance (LP) horses, were those horses that fulfilled the daily session of the avoidance-learning test. b All horses, i.e. performing horses and non-performing horses in avoidance-learning test.
test and the avoidance-learning test, as conducted in the present study, trigger the individual horse to exhibit different, i.e. no-overlapping, aspects of its personality. Although we possibly succeeded in quantifying several aspects of personality in horses we would like to emphasise that it is likely that these tests do not cover all aspects of the horse’s personality. Depending on the goal for which quantification of personality is desired, different tests, as yet to be developed, might be more powerful. 4.2. Quantifying performance of 3-year-olds Starting point for defining quantitative measures of performance is the optimal definition of performance, given the breeding goal and prospected career of the horses under examination. In the present study, horses were bred and trained to continue in a show-jumping career. Of course, one relevant aspect of performance is the purely technical jumping skill, like the number of correct jumps. But additionally, for a horse to succeed in a jumping career, it should also possess certain qualities of personality that enables it to compete successfully under various challenging conditions. Horses that will shy and rear frequently from new objects or fences, or horses that will easily refuse to jump, are not expected to be winners. Thus, in order to obtain a summary measure of performance, we used a PCA to create a variable that included both technical as well as personality aspects. The first component of
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this PCA (PerfC1) accounted for 43.2% of the variation. The average percentage of correct jumps during eight training days loaded positively on this component, the total duration to complete a novel course and the frequency of refusals and occurrences of rearing loaded all negatively on this component. This component was regarded as the operational measure of performance in the present study. Along the way in reaching the final performance there might yet be another measure, more indirect, related to performance: trainability. In the present study, we measured trainability as the relative improvement over a period of time, i.e. the relative increase in the percentage of correct jumps between day 1 and day 8 of the training period at the Equestrian Centre. Although the slope of the line in Fig. 2 does not immediately suggests any improvement, this is masked by the fact that the height and width of the fences was increased every training day in order to achieve an average percentage of correct jumps of around 80%. Hence, the seemingly relative slightly improvement of 5.2% over the eight training days for the trained horses does not indicate that these horses hardly improved. Despite the daily increases in the height and width of the fences these horses maintained an average of 80–85% correct jumps, therefore they did indeed improve. Furthermore, the results suggest that the untrained horses managed to improve their performance slightly more compared to the trained horses. 4.3. Performance predicted by personality traits The possibility of predicting the performance of horses at an early age already, is favourable for humans and horse. For men it would save a tremendous amount of time and money when investments are made in only those horses that are reliably expected to perform well. For the individual horse, it can be argued that the well-being of the horse during the life-span is optimised when the horse’s abilities, both physically as well as mentally, are matched with its use. Although the physical abilities of jumping horses are of major importance in order to succeed in a show-jumping career, the horses should also possess a certain personality to compete under various challenging conditions. In the present study, attempts were made to predict show-jumping performance, i.e. jumping correctly and not refusing and rearing in a novel course, at the age of 3 by personality as measured in personality tests earlier in life. Differences in putative measures of personality were found to account for up to 63% of the variation in show-jumping performance. When performance was predicted by separate variables, as measured in behavioural tests, the variation that was accounted for appeared to be higher than when principal components of behavioural variables were included in the regression model. Previously (Visser et al., 2001), we assumed that the principal components we derived reflect basic underlying personality traits. The present results show that these personality traits do not represent the best characteristics to predict jumping performance as 3-year-olds. It appeared that when only ‘learning-performers’ of the avoidance-learning test were used in the analysis, the variation in show-jumping performance that was accounted for by personality traits increased compared to when all horses were included. This means that the prediction of show-jumping performance by personality traits was more accurate when only those horses were considered that performed in a learning test. The observation that horses subjected to a learning test could be divided into performers and
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non-performers, i.e. animals that failed to complete the test, has been discussed in detail in a previous paper (Visser et al., 2003a). The relationship between this classification and the prediction of show-jumping performance is intriguing. Few published papers are available documenting the phenomenon that a certain category of animals, labelled as ‘non-learning-performers’ in our work with horses, fail to perform a learning test. Apart from Teskey et al. (1998), who made notice of ‘non-learning-performing’ behaviour in voles tested in a radial maze with eight arms, two equine studies reported that some horses could be classified as non-performers in a learning test (Mader and Price, 1980; Marinier and Alexander, 1994). In these latter studies, it was hypothesised that emotionality represented an important factor associated with ‘non-learning-performing’ in horses. However, this hypothesis was not convincingly supported by results obtained in our own experiment (Visser et al., 2003a). Further analysis revealed that the level of show-jumping performance did not differ between ‘learning-performers’ and ‘non-learning-performers’. We propose two possible explanations underlying the marked differences between the outcomes of regressions with or without ‘non-learning-performing’ horses included in the dataset. Firstly, it might be that in ‘non-learning-performing’ horses, in contrast to ‘leaning performing’ ones, there is no relationship between putative measures of personality and show-jumping performance. Consequently, including ‘non-learning-performers’ in the regression analyses attenuates the quality of fit in comparison with regression analysis without ‘non-learning-performers’. Secondly, the relationship between putative measures of personality and show-jumping performance may be different for ‘non-learning-performing’ horses in comparison with ‘learning-performing’ ones. In this latter case, the prediction of show-jumping performance in ‘non-learning-performing’ horses, based on measures of personality, may be as good as the prediction of show-jumping performance in ‘learning-performing’ horses, but with the use of a different regression model. A tendency towards a significant interaction between being a ‘learning-performer’ or ‘non-learning-performer’ with a co-variable (latency to touch the novel object) on the measure of show-jumping performance points in this direction. However, the present study yielded too few horses, categorised as ‘non-learning-performers’, to investigate this aspect in more detail. Hence, it is stressed that further research on the predictability of performance by personality traits should focus on the possible different relations of performers and non-performers in a learning task with respect to show-jumping performance. Considering the regression for the performers it appeared that three variables, namely ‘tail high’, ‘latency time to touch the novel object’, and ‘standing still in front of the bridge’, that were used as predictors in the first year were also needed in the prediction in the second year. It is commonly believed that the postural tonus, i.e. head and tail carriage, of the horse reflects the horse’s internal state. When evaluating horses’ jumping capacities for instance, only those horses are seriously being evaluated that display a normal postural tonus. Those horses that display a high postural tonus are thought to be too nervous; the high postural tonus prohibits the relaxation of the muscles in the back and hence has a negative influence on the jumping capacities. From a biological point of view, it is commonly believed that a horse elevates its tail when there is an intention movement to move faster. Additionally, the tail is elevated as with investigative approach, approach or avoidance conflict or in frustrations
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conflicts (Kiley-Worthington, 1976). The general assumption that a high tail carriage was caused by nervousness of the horse, is however not supported by the results of the present study. There was no correlation between a heart rate measure generally used for stress assessment (heart rate variability, RMSSD) and ‘tail high’, nor between ‘latency time to touch the novel object’ (a measure putatively related to investigative behaviour) and ‘tail high’. Although the variable ‘tail high’ was included in the regression to predict performance in both the first and the second year, the coefficient signs of this variable was reversed during the second year. ‘Tail high’ contributed negatively to the prediction of show-jumping performance in the first year and positively in the second year. The reason for this inversion in unclear. Also the other two variables, ‘standing still bridge’ and ‘latency to touch the novel object’ showed a reversed phenomenon. It is suggested that the following two things might have contributed to this inversion. Firstly, although the behavioural variables showed excellent individual consistencies within years, between years consistencies were weak (Visser et al., 2001). Hence, it can be speculated that this inversion is caused by the same horses that caused the inconsistency between years. Secondly, it is speculated that the meaning the variables changed during the maturation period. In sum, the present study indicates that it is possible to predict a substantial part of performance by personality traits measured earlier in life. The possible different relation between show-jumping performance for horses failing to perform a learning task needs further investigation. The implication for the horse industry of the present results is that it seems likely that performance can be predicted, at least for a substantial part, by personality traits earlier in life. Yet, further research is needed to investigate the overall picture. Firstly, additional aspects (not personality related variables) should be included in the regression model to predict performance in show-jumping. For instance, the variables related to the development of bone structure or co-ordination. Secondly, the performance in show-jumping, as used in the present study, should only be seen as an indication of future performance. It still has to appear whether the performance of a 3-year-old, as measured here, is comparable to the performance of a 10-year-old in competition. Thirdly, the performance of an animal that is ridden is obviously also dependent on the abilities and personality of the rider. Hence, future research should study the match between horse and rider. Presumably one horse matches better with one rider than with another and hence they will achieve a more satisfying performance. And fourthly, future research could focus on the prediction of other performances (e.g. leisure, dressage, eventing, etc.) but show-jumping by personality aspects. It might be possible that different variables of the same test predict performance other than show-jumping.
Acknowledgements This longitudinal study was enabled by the enthusiastic participation of numerous persons. Firstly, we are grateful to all students that participated in this project: Godelieve Kranendonk, Elisa Kroese, Birgit Brenninkmeijer, Margriet Visch, Femke Schothorst, Dyane van Huisstede, Tine Geurts, Sylvia Oude Veldhuis, Eske Derks, Damay Asjee and Chantal
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Kapteijn. Secondly, we thank the riders of the Equestrian Centres in Sweden (Flyinge) and in The Netherlands (Deurne) for their participation and braveness. Thirdly, we are grateful for the statistical help from the institution, especially to Willem Buist. And fourthly, we wish to thank the employees of the Research station for Animal Husbandry (Lelystad) and the National Equestrian Centre (Deurne) for their hospitality and assistance.
References Anderson, M.K., Friend, T.H., Evans, J.W., Bushong, D.M., 1999. Behavioral assessment of horses in therapeutic riding programs. Appl. Anim. Behav. Sci. 63, 11–24. Cator, R., 1991. Performance evaluations of racing thoroughbreds. J. Equine Vet. Sci. 11, 183–190. Cooper, J.J., 1998. Comparative learning theory and its application in the training of horses. Equine Vet. J. Suppl., 39–43. Egloff, B., Gruhn, A.J., 1996. Personality and endurance sports. Pers. Indiv. Differ. 21, 223–229. Erhardt, H.W., Schouten, W.G.P., 2001. Individual differences and personality. In: Keeling, L., Gonyou, H.W. (Eds.), Social Behaviour in Farm Animals, pp. 333–352. Evans, J.W., Borton, A., Fintz, H.F., VanVleck, L.D., 1977. The Horse. Freeman, San Francisco. Fiske, J.C., 1979. Behavior and learning in horses—applications in management and training. Southwestern Vet. 32, 37–44. Fiske, J.C., Potter, G.D., 1979. Discrimination reversal learning in yearling horses. J. Anim. Sci. 49, 583–588. Hausberger, M., Scolan, N.L., Bruderer, C., 1998. Le temperament du cheval: facteurs en jeu et implications practiques. J. Res. Equine 24, 159–170. Heird, J.C., Lennon, A.M., Bell, R.W., 1981. Effects of early experience on the learning ability of yearling horses. J. Anim. Sci. 53, 1204–1209. Heird, J.C., Lokey, C.E., Cogan, D.C., 1986a. Repeatability and comparison of two maze tests to measure learning ability in horses. Appl. Anim. Behav. Sci. 16, 103–119. Heird, J.C., Whitaker, D.D., Bell, R.W., Ramsey, C.B., Lokey, C.E., 1986b. The effects of handling at different ages on the subsequent learning ability of 2-year-old horses. Appl. Anim. Behav. Sci. 15, 15–25. Hernandez, J., Hawkins, D.L., 2001. Training failure among yearling horses. Am. J. Vet. Res. 62, 1418–1422. Kiley-Worthington, M., 1976. The tail movements of ungulates, canids and felids with particular reference to their causation and function as displays. Behaviour 56, 69–115. Le Scolan, N., Hausberger, M., Wolff, A., 1997. Stability over situations in temperamental traits of horses as revealed by experimental and scoring approaches. Behav. Process. 41, 257–266. Mader, D.R., Price, E.O., 1980. Discrimination learning in horses: effects of breed, age and social dominance. J. Anim. Sci. 50, 962–965. Marinier, S.L., Alexander, A.J., 1994. The use of a maze in testing learning and memory in horses. Appl. Anim. Behav. Sci. 39, 177–182. Martin, B.B., Reef, V.B., Parente, E.J., Sage, A.D., 2000. Causes of poor performance of horses during training, racing, or show-jumping: 384 cases (1992–1996). J. Am. Vet. Med. Assoc. 216, 554–558. McCall, C.A., 1990. A review of learning behavior in horses and its application in horse training. J. Anim. Sci. 68, 75–81. Rundgren, M., Nordin, A., 1997. Personality profile and simple learning tests for horses, Vienna. Sommer, H., Barz, A., Lindner, A., 1996. Testing horses for character and temperament. Tierarztliche Umschau 51, 641–643. Teskey, C.G., Ossenkopp, K.-P., Kavaliers, M., Innis, N.K., Boon, F.H., 1998. Individual differences in radial maze performance and locomotor activity in the meadow vole. Microtus Pennsylvanicus Physiol. Behav. 65, 55–561. Visser, E.K., Van Reenen, C.G., Hopster, H., Schilder, M.B.H., Knaap, J.H., Barneveld, A., Blokhuis, H.J., 2001. Quantifying aspects of young horses’ temperament: consistency of behavioural variables. Appl. Anim. Behav. Sci. 74, 241–258.
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295
Visser, E.K., Van Reenen, C.G., van der Werf, J.T.N., Schilder, M.B.H., Knaap, J.H., Barneveld, A., Blokhuis, H.J., 2002. Heart rate and heart rate variability during a novel-object test and handling test in young horses. Physiol. Behav. 76, 289–296. Visser, E.K., Van Reenen, C.G., Rundgren, M., Zetterqvist, M., Morgan, K., Blokhuis, H.J., 2003. Responses of horses in behavioural tests correlate with temperament assessed by riders. Equine Vet. J. 35 (2), 176–183. Visser, E.K., Van Reenen, C.G., Schilder, M.B.H., Barneveld, A., Blokhuis, H.J., 2003a. Learning performances in young horses using two different learning tests. Appl. Anim. Behav. Sci. 80, 311–326.