Towards a more objective assessment of equine personality using behavioural and physiological observations from performance test training

Applied Animal Behaviour Science 135 (2011) 277–285

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Towards a more objective assessment of equine personality using behavioural and physiological observations from performance test training Uta König von Borstel ∗ , Stephanie Pasing 1 , Matthias Gauly Department of Animal Science, University of Goettingen, Albrecht-Thaer-Weg 3, 37075 Goettingen, Germany

a r t i c l e

i n f o

Article history: Accepted 4 October 2011 Available online 27 October 2011 Keywords: Horse Personality Behaviour Heart rate variability Riding Performance test

a b s t r a c t Current definitions of horse personality traits are rather vague, lacking clear, universally accepted guidelines for evaluation in performance tests. Therefore, the aim of the present study was to screen behavioural and physiological measurements taken during riding for potential links with scores the same horses received in the official stallion performance test for rideability and personality traits. Behaviour, heart rate (HR) and HR variability from thirty-six stallions participating in a performance test were recorded repeatedly during their performance test training. Using the coefficient of determination, regression analysis revealed that about 1/3 of variation (ranging between r = 0.26 (“constitution” (i.e. fitness, health)) and r = 0.46 (rideability)) in the personality trait scores could be explained by selecting the three most influential behaviour patterns per trait. These behaviour patterns included stumbling (with all traits except character), head-tossing (temperament, rideability), tail-swishing (willingness to work), involuntary change in gait (character) and the rider’s use of her/his hands (constitution, rideability), voice (temperament) or whip (constitution). Subsequent mixed model analysis revealed a significant (P < 0.05) influence of the behaviour pattern “horse-induced change in gait” on character (−0.98 ± 0.31 scores per additional occurrence of change in gaits), of head-tossing (−0.25 ± 0.08 scores) and rider’s use of voice (−0.51 ± 0.25; P = 0.0594) on temperament, and of stumbling on each of the following: willingness to work (−2.5 ± 1.2), constitution (−2.5 ± 1.2 scores; P = 0.0516) and rideability scores (−3.3 ± 1.4). In addition, constitution scores tended (P = 0.0889) to increase with higher low frequency/high frequency heart rate variation ratios (LF/HF), indicating a shift towards sympathetic dominance and thus a higher stress load in horses with higher scores for constitution. Rideability scores from the training phase were also significantly influenced by head-tossing (−0.5 ± 0.1), and in addition rideability scores from the final test were influenced by the training rider, ranging between average estimated rideability scores of 6.8 ± 0.4 for one training rider and 8.36 ± 0.3 scores for another training rider. Horses ridden with their nose-line predominantly behind the vertical received higher scores for rideability (8.3 ± 0.3) than horses ridden with their nose-line at the vertical (7.7 ± 0.2). These findings indicate that either judges perceive horses to have a better rideability when they readily offer a more extreme poll flexion, or that riders make use of horses’ better rideability by imposing a more extreme poll flexion. Several of the above described associations, but also of the non-existing links (e.g. no association between shying or heart rate and temperament) between behaviour patterns and scores for personality traits are rather surprising, warranting further investigation regarding the underlying causes of these relationships. Some of these behaviour patterns should be considered when redesigning

∗ Corresponding author. Tel.: +49 551 39 101 39; fax: +49 551 39 5587. E-mail address: [email protected] (U. König von Borstel). 1 Present address: University of Veterinary Medicine Vienna, Clinic for Obstetrics, Gynaecology and Andrology, Veterinärplatz 1, A-1210 Wien, Germany. 0168-1591/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.applanim.2011.10.007

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the current guidelines for evaluation of personality traits during breeding horse performance tests, ultimately leading to improved genetic selection for equine personality traits. However, ethical implication of defining aversive behaviour such as head-tossing as an indicator of, for example, poor temperament, should not be neglected when devising new guidelines: such aversive behaviour may in fact be an indication of inadequate training techniques rather than poor horse personality. © 2011 Elsevier B.V. All rights reserved.

1. Introduction In many European countries, riding horse breeding and selection is based on a sophisticated system of evaluation and selection steps, including data collection during breeding shows and sport competitions as well as special performance tests (Koenen et al., 2004). Performance tests are designed to assess horses’ performance and breeding aptitude under standardized conditions, and are conducted either as field (duration of 1-day) or on-station (duration of several weeks at special facilities) tests. Passing of such a performance test is mandatory for young stallions to keep their breeding licenses. During on-station tests, stallions are judged for the gaits under the rider, jumping ability, as well as rideability and the personality traits labeled “character” (i.e. behaviour during handling), “temperament” (i.e. attention, reactivity), “willingness to work” (i.e. braveness, willingness, ability to learn), “constitution” (i.e. fitness, health, stamina). However, the current evaluation of personality traits in horse breeding has a number of downfalls: (1) There is a lack of clear definitions of the individual personality traits as well as a lack of universally accepted guidelines for evaluation of these traits (see Pasing et al., 2011). (2) This lack of suitable guidelines leads to inflated scores with low variation resulting in most horses receiving the same rating (König von Borstel et al., under review). (3) Personality traits are evaluated only during performance tests on station, i.e. more than 95% of all riding horses (FN, 2006, 2009) are never evaluated regarding their personality traits. Taken together, these problems result in genetic selection for personality traits in horse breeding being hardly effective. Indeed, stallions with insufficient scores in the performance traits may nevertheless pass the performance test due to very high, however unsubstantiated, personality scores. Several strategies have been suggested for improving the current situation. These strategies include the introduction of temperament tests into both station (Janiszewska et al., 2004) and field (Graf et al., 2010) performance tests in order to allow for a more objective assessment of certain personality traits such as temperament (i.e. reactivity in particular) or ease of handling. With several breeding associations such as the Franches Montagnes horses, the German association for Arabian Sport horses, the Hanoverians and formerly the Hessian Warmblood horses, these tests are already mandatory (Beuing et al., 1998; SFZV, 2001; Burger et al., 2003; SFZV, 2007; ZSAA, 2011) or provided on a voluntary basis (Christmann, 2005). However criticism includes concerns that horses’ behaviour in such tests is readily trainable, if the specific tasks are known before the test (Baumgartner et al., 2009). While trainability or manipulation certainly is an issue, the same applies

to other traits evaluated for horse breeding, or indeed with other species such as dairy cattle, too (e.g. Kuhn and Freeman, 1995). In reality, most breeding organizations and breeders use such tests mainly for marketing purposes rather than for evaluation of innate personality traits (Christmann, 2005). Also, temperament tests are generally designed to yield information on a few selected traits such as fear reactivity and ease of handling, but other important traits such as willingness to work may not be reflected adequately. Thus, an additional strategy for making personality assessment more objective could include the development of new guidelines including concrete descriptions of behaviour patterns and/or physiological measurements shown during regular training and relating them to specific personality trait scores. However, to date little information on specific behaviour patterns and their relationship with personality traits is available. In addition, there is no consensus on the definitions of the individual personality traits. A wide range of definitions of temperament have been given in the scientific literature (Goldsmith et al., 1987; Bates, 1989; Cloninger et al., 1993) and similar disagreement in the definition of temperament exists among breeding authorities (Pasing et al., 2011; König von Borstel et al., under review). The situation is rather worse with traits such as willingness to work or constitution (Pasing et al., 2011). Therefore, the objective of the present study was to take behavioural and physiological observations on horses and riders during regular performance test training, and subsequently to relate these observations to the scores these horses obtained for the different personality traits. 2. Materials and methods 2.1. Animals, riders and location A total of 36 Warmblood stallions were enrolled in the present study. All of them were participants of a 30day performance test in Germany in 2009. They were either 3 (n = 26) or 4 (n = 10) years of age and belonged to one of 8 different sport horse breeds: Westfalian (n = 14), Oldenburger (n = 6), Hanoverian (n = 5), Holsteiner (n = 5), Bavarian Warmblood (n = 2), Belgian Warmblood (n = 2), Trakehner (n = 1), Oldenburger Springpferd (n = 1). Data were collected during the stallions’ regular riding training for the performance test in the stations’ riding arena measuring 20 m × 55 m. Individual riding bouts took on average (±SD) 19.9 ± 4.6 min. Horses were ridden by a total of 6 professional riders (having obtained a vocational degree in equine management) and 4 apprentices who were all in their third year of training. This information on level of professional education, in addition to riders’ name and their discipline of specialization (dressage or show-jumping)

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was obtained via a brief personal interview. Each horse was assigned to one rider, who remained the same throughout the training and observation period of the study. The maximum number of horses per rider was 10, the minimum number was 5. One rider rode just one horse, however, this rider was set missing for the analysis of rider effects to avoid bias due to confounding of horse and rider effects. 2.2. Experimental set-up and data collection Each horse was observed a minimum of two and a maximum of five times during the four weeks performance test period: at least one observation each was taken during the second week of the performance test training and during the fourth week of performance test training. Training ensued in changing groups of 4–6 horses ridden together in the arena, and horses of each group were observed simultaneously. Horses were equipped with a heart rate monitor (Polar 800XS; Polar Electro Öy, Finland) prior to saddling, and recording was set to continuous (beat-to-beat interval) recording. Behavioural data was collected from video recordings obtained simultaneously with heart rate recordings. The camera for these video recordings was mounted in the middle of one of the 20 m sides of the arena. This set-up resulted in a small fraction of the arena (i.e. the two corners close to the camera, corresponding to ca. 15 m on the outside track) being out of sight for the camera. However, since this was equal for all horses, it was not deemed problematic. A list and brief description of behaviour and physiological variables observed in horse and/or rider is given in Table 1. The categorical variables were recorded only when the horse was at a right angle to the camera, i.e. when riding parallel to the short-sides of the arena. For evaluation of head posture, one video-frame was used each time exactly when the horse’s head crossed the arena’s centre line. Ear position was classified per passing of the short side into one category (Table 1), depending on the predominant type of observations. Subsequently, based on the highest proportion of different categories, the predominant category was determined for both variables on a per-ride basis and assigned to that ride. With all other behavioural observations, the total frequency of occurrence was recorded and for information purposes (Table 1) converted into frequencies per hour of riding. Riders were observed in addition to the horses in order to obtain an indication of the type and degree of interaction with the horse. To allow for correction of heart rates and frequencies of behaviour patterns for differences in physical exertion and length in observation time, the overall duration per ride as well as the duration of time spent in the individual gaits walk, trot, canter, and halts, plus the number of transitions between gaits was recorded. When the performance test was concluded, horses’ official scores for personality traits (character, temperament, willingness to work, constitution, overall personality (= the mean of the previous four traits), and rideability) and, for the sake of comparison, the scores for performance traits (walk, trot, canter, jumping ability) were obtained from the testing station. These scores included scores for personality and performance traits as assigned by the training judge for horses’ performance during the 30-day training phase, the individual

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scores for horses’ performance in the 1-day final test (performance traits and rideability only), as well as the final, combined scores for individual traits and for the pooled traits dressage, show-jumping and overall performance. In the final test, rideability is assessed by a test-rider unfamiliar with the horse, rather than by a judge from the ground. Personality traits are not evaluated again in the final test, owing to the short duration of the final test. Hence for personality traits just one score per trait and horse plus a combined personality score was available. For rideability and performance traits three scores were available: the score from the training phase, the score from the final test and the overall score, combining the equally weighted results from training and test phase. 2.3. Statistical analysis Mean heart rate and the heart rate variability parameters RMSSD (root mean square of successive beat-to-beat time interval differences) and LF/HF ratio (ratio of low frequency (0.04–0.15 Hz) and high frequency (0.15–0.4 Hz) heart rate variation) were calculated per ride using the software Kubios (Kuopio, Finland). Statistical analysis was conducted using SAS 9.1 (SAS Institute Inc., USA, Cary, North Carolina, USA). Heart rate, heart rate variability parameters, all behaviour traits and scores for each personality trait (character, temperament, willingness to work, constitution), overall personality, rideability, as well as for the gaits (walk, trot, canter) and jumping ability were each considered a dependent variable. Each dependent variable was analysed using a regression (Procedure Reg) and a forward selection approach, considering all linear variables (scores, behaviour observations, heart rate) as potential covariables. In order to obtain an indication of how well the independent variables can explain the respective dependent variable, the coefficient of determination was used to select the best model (i.e. selecting from all possible combinations of independent variables the combination explaining the largest amount of variation in the dependent variable) with a maximum of 3 independent variables. In addition, a mixed model (procedure mixed) was applied, considering rider, age, predominant head posture (at, in front, or behind vertical) and ear posture (forward, backward, moving) as fixed factors and horse a random factor accounting for repeated observations per horse. All potential co-variables from the regression model were tested for significance, but removed if they were not significant (P > 0.1). Pearson correlations were calculated between scores for the different personality traits both from training and final test as well as the overall score for gaits and show-jumping in order to obtain an indication of the interrelatedness of the different traits. 3. Results With the exception of the trait stumbling, which was seen only in three horses during the observation period, all recorded behavioural variables were seen frequently (Table 1) and in at least eight and at most 26 different horses (change in gait and head tossing for minimum and maximum number of different

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Table 1 Observed behaviour patterns and physiological parameters in the horse and rider, their respective mode of recording and percentage or frequency of occurrence per hour of riding. Parameter

Variable type

Frequency per h ± SE

Description

Horse related Change in pace

Count

0.41 ± 0.04

Snorting Tail-swishing Head-tossing

Count Count Count

1.10 ± 0.09 13.4 ± 0.88 2.60 ± 0.14

Crabbing

Count

0.90 ± 0.08

Attempted buck

Count

0.45 ± 0.05

Stumbling

Count

0.06 ± 0.01

Shying Ear position Pointed forward

Count Categoriesa

1.67 ± 0.11

The rhythm of a gait is interrupted because the horse attempts to change into a faster or slower gait The horse exhales air forcefully, producing a snoring sound The tail moves horizontally (other, e.g. vertical movement disregarded) The horse throws its head forcefully upwards and/or sideways, pushing against the reins The horse moves sideways, attempting to evade taking up additional load with the hindlegs The horse arches the back and jumps with lowered head with buck both hind legs upwards The rhythm of a gait is lost, often (but not limited to) because the horse hits its own leg with another leg The horses shows a startle reaction with a subsequent attempt to flee

18.4%

Pointed backward

16.3%

Moving

65.3%

Head posture At vertical Behind vertical

Categoriesa 69.4% 22.2%

In front of vertical Heart rate RMSSD

Mean Mean

LF/HF ratio

Ratio

Rider related Hand aids Leg aids Use of whip Use of voice

Count Count Count Count

0.64 ± 0.07 1.86 ± 0.18 0.82 ± 0.10 0.49 ± 0.04

Count

33.0 ± 0.62

Transitions

The horses’ ears are immobile with the pinna pointed forward for the entire short side of the arena The horses’ ears are turned backward, however, without being flattened The horse continues to move the ears between forward and backward positions (including brief bouts with one ear pointed forward, the other backwards)

0%

The horses’ noseline is approximately at the vertical The horses’ noseline is at least 10 degrees (ca. one hand-width at the nostrils) behind the vertical Opposite definition of “behind vertical” Average heart rate per ride Heart rate variability: root mean square of successive beat-to-beat differences Ratio between low and high frequency heart rate variability band powers Rider visibly moves the hand in relation to the body Rider visibly applies pressure with legs on the horse The rider touches the horse with the whip The rider talks to the horse either in a calming voice or in an attempt to urge/reprimand the horse The rider asks the horse to change the gait (halt, walk, trot, canter) either from slower to faster or vice versa

a Values are given in percent of total observations. Values do not add up to 100% due to missing observations e.g. when horses were covered by other horses in the video frame.

animals, respectively). The coefficient of determination from the regression analysis revealed that a substantial proportion of horses’ scores for character (r = 0.38), temperament (r = 0.38), willingness to work (r = 0.35), constitution (r = 0.26), and rideability (r = 0.42) could be explained by the three most influential behaviour patterns per trait. These behaviour patterns included stumbling (with all traits except character), head-tossing (temperament, rideability), tail-swishing (willingness to work), involuntary change in gait (character) and the rider’s use of her/his hands (constitution, rideability), voice (temperament) or whip (constitution). The behavioural trait stumbling stands out, occurring in 4 of 5 (i.e. all except character) best fitted regressions, but has to be viewed in consideration of its rare occurrence. Similarly, head-tossing was selected for temperament, as well as for both rideability scores assigned by the judge during training phase and by the test-rider during the final test.

Table 2 gives an overview of linear factors significantly influencing personality scores according to the mixed model analysis. Overall personality scores as well as the scores for the individual personality traits were significantly influenced by a number of behaviour traits. For example, character scores were significantly influenced by a horse-induced change in gait, with scores dropping by 1 ± 0.31 scores per observed change in gait (Table 2). Horses that were ridden with their heads predominantly considerably (i.e. >10◦ ) behind the vertical received higher personality scores (P = 0.0406, F1,25 = 4.41) as well as higher rideability scores (8.3 ± 0.25 vs. 7.7 ± 0.18; P = 0.0253; F1,29 = 5.56) than those ridden with their noseline predominantly at or only slightly behind the vertical (Fig. 1). In addition, younger (3-years of age) stallions received significantly higher scores for rideability in the training phase compared to 4-year old stallions (8.3 ± 0.1 versus 7.7 ± 0.2; F1,28 = 8.96; P = 0.0057). There were also

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Table 2 Influence of behaviour patterns and heart rate variability (LF/HF ratio) on scores for personality traits. The strength of influence indicates the change in personality score per additional occurrence of the behaviour trait during the observation period. Personality trait

Physiological/behaviour trait

Influence ± SE

F, P-values

Overall Personality

Stumbling Head-tossing Rider’s use of voice Horse-induced change in gait Head-tossing Rider’s use of voice Stumbling LF/HF ratio Stumbling Stumbling Head-tossing Head-tossing Head-tossing

−1.8 −0.1 −0.3 −1.0 −0.3 −0.5 −3.5 0.008 −2.7 −3.3 −0.5 −0.5 −0.4

F1,24 = 10.82; P = 0.0031 F1,24 = 5.22; P = 0.0315 F1,24 = 5.29; P = 0.0304 F1,29 = 9.78; P = 0.0040 F1,27 = 8.94; P = 0.0059 F1,27 = 3.87; P = 0.0594 F1,29 = 7.14; P = 0.0123 F1,29 = 3.10; P = 0.0889 F1,30 = 5.5; P = 0.0250 F1,28 = 6.52; P = 0.0164 F1,28 = 17.95; P = 0.0002 F1,25 = 4.05; P = 0.0551 F1,28 = 7.58; P = 0.0102

Character Temperament Constitution Willingness to work Rideability (training) Rideability (test rider) Rideability (final score)

Score (1 = very poor – 10 = very good)

considerable differences of up to 1.1 ± 0.85 scores from the final test between individual training riders (F5,25 = 2.95; P = 0.0317). Except for a tendency in constitution for LF/HF, none of the other personality traits was influenced by heart rate or heart rate variability, and heart rate and RMSSD were not influenced by any of the observed behaviour patterns (P > 0.1). However, the LF/HF ratio significantly increased with increasing use of the rider’s hands (+0.20 ± 0.08; F1,28 = 2.44; P = 0.0211) and was higher, the more attempts to buck a horse showed (+0.29 ± 0.10; F1,28 = 2.79; P = 0.0094). In addition, it tended to be higher with additional occurrences of stumbling (+0.87 ± 0.45; F1,28 = 1.91; P = 0.0664). The overall, combined score for dressage tended to be higher, the more often the riders gave visible hand aids (0.41 ± 0.21; F1,25 = 3.74; P = 0.0647) as well as whip aids (0.27 ± 0.15; F1,25 = 3.15; P = 0.0882). However, the more often the riders used their voice as an aid, the lower the dressage scores were (−0.93 ± 0.35 scores per use of voice; F1,25 = 7,14; P = 0.0131). Head tossing likewise reduced dressage scores by 0.34 ± 0.11 scores per occurrence (F1,25 = 9.69; P = 0.0046). When considering the individual gaits (walk, trot, canter) variation in scores could 10 9 8

a

b

A

B

7 6 5

at behind vertical vertical

at behind vertical vertical

rideability (final sc ore)

overall personality

4 3 2 1

Fig. 1. Influence of horses’ predominant head posture (white bars = at vertical; black bars = >10◦ behind vertical) on final rideability scores and overall personality scores. Different letters indicate statistically significant differences within score-type at P < 0.05.

± ± ± ± ± ± ± ± ± ± ± ± ±

0.5 0.1 0.1 0.3 0.1 0.3 1.3 0.004 1.2 1.4 0.1 1.3 0.1

generally not be explained by horse behaviour patterns, but trot was influenced by the rider’s use of hands, and walk was influenced by the rider’s use of voice. No such association of the rider’s use of aids with scores was seen in the overall combined score for show-jumping, but the more head-tossing was observed, the lower the scores for show-jumping were (−0.37 ± 0.14; F1,23 = 6.57; P = 0.0174). With the exception of the trait character (P > 0.05) and the pair temperament-constitution, scores for all personality traits were positively correlated with each other (P < 0.05), with correlation coefficients ranging between 0.46 (constitution-rideability) and 0.79 (temperamentrideability). 4. Discussion The present analysis showed that there is a considerable relationship between the different, presently evaluated personality traits and certain behaviour patterns during riding, such as stumbling, head tossing, and the horses’ head posture. However, a strong association between behavioural observations and scores from personality evaluation is an ambivalent finding, since we (Pasing et al., 2011) showed earlier that the present scores lack objectivity and may not be a good reflection of the true, underlying trait. This notion is further supported by the fact that the scores for different personality traits show high phenotypic correlations in both horse breeding in general (König von Borstel et al., under review) and in the present study. Moreover, a few behaviour patterns significantly influenced several different personality traits in a very similar manner. Especially the latter finding suggests that judges do not clearly distinguish between the different personality traits but rather use their overall impression of a horse to then assign scores to the different, vaguely defined personality traits. Rothmann et al. (2010) also used behavioural observations during riding horse inspection in an attempt to objectify evaluation of temperament. They found considerable individual variation for traits such as restlessness when required to stand still in front of the judges. In addition, restlessness was negatively associated with rideability and free jumping scores (Rothmann et al., 2010),

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disproving the widespread concern that calm horses tend to lack the qualities required for high-performance horses. On the other hand, their (Rothmann et al., 2010) data included observations on horses in hand rather than under the saddle. Both approaches may provide important results as reasonable correlations exist between behaviour in hand and under saddle when exposed to the same temperament test (König von Borstel et al., 2011a). However, in the case of riding horses, the evaluation of behaviour under saddle may be particularly important, reflecting best the practical circumstances horses will be priced for when marketed. For example, although head-tossing can be observed both in hand as well as under the rider, the motivation for head-tossing is likely a different one in the two situations: during riding it is considered to be mainly a sign of conflict due to incorrect negative reinforcement (de Cartier d‘Yves and Ödberg, 2005; McGreevy et al., 2005), resistance against the pain resulting from pressure of the bit (Cook, 2003; Ludewig et al., 2011), or the head posture induced by pressure on the bit (von Borstel et al., 2009). In contrast, when presented in hand, the horse is allowed to carry its head with less poll flexion, and rein contact is generally less steady. Thus, behaviour patterns such as head-tossing observed in hand or during riding may result from different underlying motivations (e.g. playfulness or unwillingness to follow or submit to the handler versus the above-mentioned factors) and may thus not be directly comparable. Other non-personality related, underlying traits are also relevant in the expression of behaviour. For example, Lesimple et al. (2010) demonstrated that horses with back pain spent more time in undesired postures such as a high, hollow neck during riding. Similarly, horses showing more frequently head-tossing may simply be more sensitive in the mouth, more uncomfortable with poll flexion, or paired with a less skilled or empathetic rider. In this case, head-tossing would merely be a measure of pain or sensitivity, as suggested by several authors (e.g. Cook, 1999; de Cartier d‘Yves and Ödberg, 2005). In contrast, the present findings suggest that judges mainly perceive behaviour patterns such as head-tossing as an indicator of poor temperament or refusal to co-operate and work. From a practical point of view it could generally be considered a reasonable approach to actively select horses, for example, against head-tossing regardless of the underlying cause. Genetic evaluation of quantitative traits based on phenotypic records always implies that there is a considerable proportion of variance caused by environmental factors such as housing conditions (Rivera et al., 2002; Søndergaard and Halekoh, 2003; Søndergaard and Ladewig, 2004) or the previous experience and present interaction with handler (Hausberger and Muller, 2002; Henry et al., 2006) and rider (Deuel and Lawrence, 1988; Hausberger et al., 2004; König von Borstel et al., 2011a). Thus the additional variance in horse behaviour added by the rider would not pose a problem from a statistical point of view. However, it may not be the best option to relate behaviour patterns such as head tossing directly to personality traits. Implying a poor temperament on the horse’s side rather than also searching for physiological discomfort in the horse or potential mistakes in the rider would set a wrong signal, from the ethical point of view. Horses would

be falsely blamed for the shortcomings of their riders and as a further consequence selection of breeding animals would be ineffective. In best case this would result in selection attempts being in vain, but in the worst case it could also direct selection towards compliant horses that suffer quietly rather than that they express their discomfort. The findings that some behaviour patterns are associated with personality and rideability scores from a performance test, but that there are limited, significant relationships between heart rate measurements and behaviour or personality scores, are in agreement with previous findings by de Cartier d‘Yves and Ödberg (2005) regarding scores from a dressage test. de Cartier d‘Yves and Ödberg (2005) discussed this lack of association in view of the possibility that the their older and well-trained horses may have formed a habit of the behaviour patterns and that they thus did not directly reflect emotional changes. However, horses of the present study were at the very beginning of their riding training. Therefore, it seems rather unlikely that these horses had already formed a habit of these behaviour patterns, thus providing some evidence against this assumption. This is further supported by the influence that the rider’s use of hands as well as stumbling and attempted bucks have on horses’ heart rate variability parameter LF/HF ratio. Rising LF/HF ratios indicate that the sympathetic modulation gains importance and accordingly indicate stress or negative emotional arousal (Task Force of the European Society of Cardiology, 1996; von Borell et al., 2007). As a consequence, the behaviour patterns stumbling and attempted bucks may be reliable indicators of stress in the horses of the present study. Further, it could be concluded that the visible use of rider’s hands causes stress in the horse. Contrary to the expectations of increasing parasympathetic dominance with increasing levels of fitness (e.g. De Meersman, 1993), higher LF/HF ratios tended to be associated with higher scores for constitution, implying that those horses experiencing more stress were considered to be physically more fit by the judge. Potentially, the more stressed horses appeared livelier, and thus healthier/fitter, to the judges. However, these impressions must have been based on observations that were not covered by the behaviour categories of our present study. Also, in spite of the significant links found in the present study, the results should nevertheless be taken with care as von Borell et al. (2007) warned, based on results by Hansen (2000), that heart rate variability measurements may only be comparable if physical activity is controlled for. Although a number of behaviour patterns and duration spent in different gaits was recorded, the exact movements of the horses were not standardized and thus may have varied. Surprisingly, the behaviour trait “shying” did not show a significant association with scores for temperament. This finding is rather unexpected since in animal research fear reactivity is considered to be one of the main components of temperament (Kadel et al., 2006; Lansade et al., 2008; Brown et al., 2009), and shying is generally assumed to be a good indicator of reactivity. Indeed, Jönsson et al. (2010) reported negative correlations between temperament scores from performance tests and the traits “spooky”, “prone to freeze” and “tense”. However, a similar

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lack of association between reactivity in novel object tests and current scores for temperament has been detected in related studies (Graf et al., 2010; König von Borstel et al., 2011b), indicating that the present evaluation for temperament does not take much of the temperament dimension reactivity into consideration. Associations of stumbling with most of horses’ personality traits are also surprising at the first glance. However, this behaviour pattern was shown only by three horses and thus the global validity of the results can be questioned as the power of the analysis is limited. Nevertheless, stumbling may reflect that a horse is overexerted with the current situation and could as such be considered a useful trait in the evaluation of constitution. Similarly, a negative influence of stumbling on rideability appears reasonable as such a stumbling horse or a horse generally lacking physical condition will be less comfortable to ride. Conversely, the negative association of stumbling with the traits character and willingness to work may indicate that judges consciously or subconsciously blame horses’ attitude or will to work, when in fact the horse is lacking physical ability. Thus, the relationship between stumbling and several personality traits points to two problems: first, it supports the observation that the different personality traits lack clear definitions and possibilities to separate the different traits from each other (Pasing et al., 2011). Second, it indicates that judges have problems to clearly distinguish between horses’ (lack of) ability and will (König von Borstel et al., under review). From the end-users’ point of view it may actually not be overly important to clearly distinguish between the reasons for why the horse shows (or does not show) a certain level of work, and it could be sufficient to simply measure the level of work shown. However, from the breeding and selection point of view it may nevertheless be important to distinguish between will and ability because they are likely determined by very different underlying genetic aspects. Moreover, from a trainer’s point of view it is important to know whether a horse has reached its physiological limits or if the horse is not willing to perform better. In the latter case, the problem may potentially be overcome by a change in training techniques, while in the former case any additional training attempts would be in vain. Therefore, further investigations are required to shed light on the differences between willingness and ability to work. The observed relationship between head posture and scores for rideability is rather unexpected. It raises the question whether horses who are more yielding and readily offer to carry their head behind the vertical are inherently the ones who are more comfortable for the rider and give the rider a better feeling, or whether riders make use of horses’ greater rideability by adjusting the reins and thus the horses’ posture such that horses carry their heads behind the vertical, perhaps because this posture is perceived to be the ideal frame. The latter would be in line with findings for example from McGreevy et al. (2010) that the majority of horses in sales-catalogues are ridden in a frame considerably behind the vertical, indicating that this posture is perceived to be the ideal posture by many riders. Especially if the latter case is true, this finding is rather disconcerting since a hyperflexed posture has been

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controversially discussed (e.g. Ödberg, 2006; van Weeren et al., 2006; McGreevy et al., 2010). Although some studies failed to find negative impacts of riding in this posture (Sloet van Oldruitenborgh-Oosterbaan et al., 2006; van Breda, 2006), in other studies it has been shown to be aversive to horses, at least when obtained coercively (von Borstel et al., 2009). Overall, the present study revealed rather surprising relationships between certain behaviour patterns as well as heart rate variability and scores for personality traits. The present findings provide a first indication of which behaviour traits may be particularly influential on present evaluation practices. However, larger sample sizes including judges from different stations are required to define more universally applicable relationships. Also, even though a large proportion of present variation in personality scores could be explained by certain behaviour patterns, using these behaviour patterns as a lone alternative for evaluation of personality may not be sufficient, since present scores have several short-comings. Combining behavioural observations during regular riding with observations from specialized temperament tests (Visser et al., 2009; König von Borstel et al., 2011b) appears to be the best approach to yield a comprehensive picture of horses’ personality traits relevant in practical situation. Additional observations of heart rate variability could potentially be used to further objectify assessment of physical fitness or general ability to cope with the situation of riding training, but dependency from technical equipment may prevent the wide-spread application of this technique in practice. In any case, a single measure alone will not suffice to significantly improve current personality assessment, because as Tschirren and Bensch (2010) put it, there is “no simple answer to a complex trait”. 5. Conclusions Several behaviour patterns shown during riding such as head-tossing and stumbling and the heart rate variability parameter LF/HF ratio show a relationship with scores from present evaluation of personality traits. Including such concrete behaviour traits in evaluation guidelines for personality traits assessed during breeding horse performance test, could improve objectivity of the present evaluation. However, as long as underlying causes of behaviour patterns are not known, from an ethical point of view, care should be taken when directly linking aversive behaviour with poor personality in the horse. Also, still important traits such as learning ability or reactivity will not be sufficiently covered by these behaviour observations. Thus, a combination of behaviour observations during riding with additional measures, such as special temperament tests, are required to cover different aspects of personality and to accomplish the ultimate goal of enhanced genetic improvement of equine personality traits. Acknowledgements We are very grateful to the head and staff of the testing station for their time and effort in supporting this study.

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