Abstract: Temperament is an important factor when working with horses. Behavioural tests have already been developed to measure certain dimensions of a horse's temperament (fearfulness, gregariousness, etc.). In order to measure the temperament more precisely, our work aimed to identify a dimension which has already been described in several species but not yet in horses, namely sensory sensitivity. Our study was based on the definition of a temperament dimension as “a behavioural characteristic stable across situations and over time”. We designed several tests for each sense and then determined whether the responses observed were correlated between situations and in time. The principle of the tests was to generate two stimuli of different intensities for each sense (e.g. two different sounds) and to measure the intensity of the horse's response (N = 26). Using Spearman rank correlations, we tested whether the responses to these different stimuli were inter-correlated. We repeated the same tests 5 months later to determine whether the responses were correlated over time. Within each sense, results show that the greater the horses' response to one stimulus, the greater their response to the other. For example, the reaction to the odour of cinnamon (time spent near the source of the odour) was significantly correlated to the reaction to lavender (R = 0.53, p = 0.004). The reactions to two different sounds or to two different tactile stimuli (von Frey filaments, or contact of a brush on the body), were also significantly correlated (R = 0.59, p < 0.0001; R = 0.38, p = 0.029). Finally, the reactions to two different tastes or to two visual stimuli tended to be correlated (R = 0.27, p = 0.09; R = 0.27, p = 0.09). However, there was no significant correlation between the responses to stimuli relating to different senses. Finally, except for the responses to odour, the responses to other sensory stimuli showed stability over a 5-month period (e.g. tactile stimulation: R = 0.71, p < 0.0001). In conclusion, our study revealed characteristics which were stable across situations and over time. The absence of links between the characteristics measured for the different senses suggests that a dimension for each sense exists (e.g. tactile sensitivity) rather than a general sensory sensitivity dimension covering all the senses.

Abstract: Methods are described to assess horses' selective grazing ability that includes choosing, sorting and the adaptive value of this behaviour. Choosing ability was tested by the experimenter presenting pairs of cut plant species that were then alternated at each presentation until the test horse had taken three bites of one of the plant pair. The results were analysed in relation to five measures of choosing behaviour: (1) the strength of the choice; (2) correspondence between first bite and the final choice; (3) constancy of the choice over a number of trials; (4) the comparison of the horses' ranking of the species over a number of trials; (5) the constancy of the linear arrangement of the plants over a number of trials. Sorting ability was tested using two methods. A mixture of two plant species was presented either in a clamp or loose in a trough. Results were based on number and weight of plant residues. The adaptive value of the behaviour related to the bitterness of toxic plants. This bitterness was represented in testing by quinine sulphate and a poisonous Senecio species. An extremely bitter substance “Bitrex” was also used in this context but was totally accepted by the horses. The horses' reactions to these substances were monitored using a behavioural score chart. The results from 12 horses revealed that the horses differed individually in their grazing ability. On this basis, the horses were classified as efficient, semi-efficient, or inefficient grazers. This finding has practical implications in deciding which horses may safely graze on pastures infested with toxic plants.

Abstract: Like most large grazing herbivores, horses select their food based on visual cues, odour, taste, texture, availability and variety. There is relatively little published information about the role of flavour in diet selection by domestic horses in comparison with other domestic and companion animals. However, previous trials investigating effects of diet flavour in stabled horses indicated significant effects on foraging behaviour and selection. In this series of three trials we aimed to determine relative acceptance by presenting flavour preference tests to eight horses. Horses were stabled and fed hay ad lib on trial data collection days plus a standard unflavoured concentrate ration at 7:30 a.m. In Trial 1, 15 flavours were separately presented in standard 100 g cereal by-product meals and the trial was replicated. Quantity consumed, time of completion, partial rejection or refusal were recorded. Order of presentation was determined by a Latin Square design. Trial data were collected on five sampling days, separated by a minimum of 1 day. Horses were presented with six flavoured meals daily; minimum 1 h between the meals. Twelve flavours were universally accepted and of these the eight flavours with fastest mean consumption times (banana, carrot, cherry, cumin, fenugreek, oregano, peppermint and rosemary) were presented in paired preference tests in Trial 2. In Trial 2, all paired combinations of the eight flavours were presented, in two tests per day at noon and 4 p.m. Presentations of the same flavour were separated by at least 1 day. Paired presentations were in 300 g cereal by-product. Presentations were terminated when approximately half of the total amount presented had been consumed. Flavour preferences were expressed as a ratio from 0 (rejection) to 1 (exclusive consumption). Paired flavour preferences produced the following rank order: fenugreek, banana, cherry, rosemary, cumin, carrot, peppermint, oregano. In Trial 3, relative consumption times of mineral pellets flavoured with fenugreek and banana were significantly reduced in comparison with unflavoured pellets. In these short-term trials, flavour had significant effects on diet acceptance, selection and consumption times.

Abstract: Responses of horses towards fear-eliciting stimuli can have important consequences for both human and horse safety. This experiment was designed to investigate behavioural and heart rate (HR) responses of horses to novel visual, auditory and olfactory stimuli. Twenty-four 2-year-old, previously unhandled, stallions were habituated to receive a food reward from a container in a test arena. Each horse was exposed to three 2 min tests in a balanced design where in addition to the feed container, either a traffic cone (visual test), white noise (auditory test) or eucalyptus oil applied to the inside of the container (olfactory test) were used as the novel stimuli. Compared to the control, less time was spent eating during all tests. There was no difference in locomotion activity in the different test situations, but presentation of the novel visual and auditory stimuli elicited significantly increased HR responses in the horses, compared to their response to the arena without novel stimuli (control), whereas there was no increase in HR response to the olfactory stimulus. However, during the olfactory test, the horses had an increased number of eating bouts and became more vigilant towards their surroundings, whereas during the visual and auditory tests, more time was spent alert towards the stimulus. The horses also took significantly more steps backwards in response to the auditory test. The heart rate responses correlated between tests and reflect a non-differentiated activation of the sympathetic nervous system, while the behavioural responses were linked to the type of stimulus.

Abstract: Current scores for equine personality traits assessed during performance tests are characterised by high means and inadequate variation, hampering genetic selection for these traits. A number of temperament and related behaviour tests have been developed in order to make assessment of equine personality more objective. However, rarely these tests have been validated for their use as a selection tool. Thus, as a first step the aim of the present study was to integrate a temperament tests into horse performance tests, in order to assess variability and repeatability of horses’ reactivity under the rider and the reliability of the judges’ assessment thereof. The temperament test was comprised of three novel stimuli, including a visual stimulus (BALL), a visual and tactile stimulus (GATE), and a visual and auditory stimulus (CANS). A total of 224 mares and stallions were subjected to the test during their participation in station performance tests for riding horses, and 133 of these horses were subjected to the test a second time either 2–3 weeks or 18 weeks after the first test. Horses were ridden in the test by professional riders, and their reactions to the stimuli were evaluated each by two judges and the rider using scores on a scale from 1 (task not concluded) to 10 (completely calm but attentive horse). Mean scores (±SD) ranged between 6.6 ± 2.4 (GATE) and 7.8 ± 2.1 (BALL), demonstrating lower means and considerably higher standard deviations than the same horses’ scores from present evaluation of the trait labelled temperament (8.1 ± 0.9) or related personality traits (e.g. character: 8.3 ± 0.8). Using variance components from mixed model analysis, inter-observer agreement between the two judges was for the individual stimuli very high (0.95 (BALL), 0.96 (GATE), 0.89 (CANS)), and there was likewise high agreement between the judges’ and the riders’ combined scores (0.93). Repeatabilities of horses’ scores were 0.72 (BALL), 0.75 (GATE), and 0.69 (CANS). Correlations to traits from the present evaluation of personality were low or non-existent, indicating that these traits are not a reflection of anxiety or fear reactivity as assessed by novel object tests. Horses’ improvement in judges’ combined scores from first to second test was not (P > 0.1) influenced by differences in time between tests, but differed between breed-types and individual riders. Also, not surprisingly, the higher horses’ scores in the first test were, the lower their improvement in the second test was (-0.45 ± 0.06 per additional score in the first test). Temperament tests using novel stimuli presented to horses under a rider may be a practical and valid tool for improving the current assessment of equine personality traits during performance tests. Considering a combination of absolute scores and horses’ improvement in scores of repeated tests, rather than measuring only absolute scores yields relevant information about horses’ personality, and at the same time it may prevent owners from deliberately training their horses for low reactions to the test-stimuli.