Abstract: We observed the behaviour of six stabled horses (stallions n = 3; geldings n = 3) in an attempt to identify behavioural measures of eating satisfaction. The horses were required to perform an operant response (pressing a button with the muzzle) in order to access a food reward in an experimental box stall. After each horse had successfully learned the experimental situation, it participated in the experimental protocol on 4 days. Horses were brought to the experimental box stall for the operant response sessions (1 h duration per session), and upon completion, they were returned to their own (home) box stalls. The number of presses for the reward was a Fixed Ratio schedule of either 3 or 12 muzzle presses (FR3, FR12) and the FR procedure for each horse was as follows: FR3 FR12 FR12 FR3 or FR12 FR3 FR3 FR12. Number of rewards obtained during each session, and behaviour and heart rate after each session were recorded for each horse. A repeated measures ANOVA showed that the number of rewards obtained in FR3 was higher than in FR12 (P < 0.05). The horses spent more time in standing-rest, (with ears rotating laterally and exhibiting a low neck position) indicating sleep, in the home box stall, after FR3 compared to FR12 treatments (P < 0.05). Mean heart rate after standing-sleep was significantly lower than mean heart rate in the home box stall (P < 0.01). These results suggest that eating satisfaction induces sleep in stabled horses, and that episodes of standing-sleep behaviour may be a useful indicator of appropriate or enhanced welfare in the horse.

Abstract: The cognitive capacity of an organism, relative to that of other species, can be assessed by using a relative measure of learning. One such measure is the ability of an organism to learn about the reversal of a discrimination. The present study compared the performance of two groups of horses on a simple discrimination reversal task when the only difference between the groups was the modality of the relevant cue. For the visual group (absence or presence of a light), the spatial position was irrelevant. For the spatial group, a spatial cue (left/right) was available and the visual cue was irrelevant. Horses in the spatial group learned the original discrimination and six reversals; they also showed evidence of learning to learn. Horses in the visual group did not reach criterion during the study. As a result, there was no evidence of learning to learn.

Abstract: Forty Danish warmblood colts in two replicates were used to investigate the effect of housing and handling in the rearing period on the reactions to humans. The horses entered the experiment after weaning and were housed either individually (n=16) or in groups of three (n=24). Half of the horses from each housing group were handled three times per week for a period of 10 min. Approach tests were performed in the home environment when the horses were 6, 9, 12, 18, 21, and 24 months old, and an Arena and Human Encounter test was performed in a novel environment when the horses were 12 and 24 months old, respectively. In the home environment, single-housed horses approached sooner and were more easily approached by a human than group-housed horses where no effect of handling was observed. Horses approached sooner and were more easily approached with increasing age. In the Arena and Human Encounter test, single-housed horses expressed less restless behaviour, more explorative behaviour, and less vocalisation than group-housed horses. Handled horses showed lower increase in heart rate during the test than non-handled horses. There was no difference between the number of times single or group-housed horses touched an unfamiliar person in the Arena and Human Encounter test but handled horses approached sooner than non-handled horses. It is concluded that the social environment affected the way horses reacted to humans when tested in the home environment but not in a novel environment. In contrast, handling affected the reactions to humans when tested in the novel environment but not in the home environment. However, handled horses also reacted less to the novel environment in general, thus indicating that handling is a mean of avoiding potential dangerous situations.

Abstract: The influence of age, dominance rank, kinship and aggressiveness over affiliative relationships and sexual behaviours were analysed in a herd of Sorraia horses, Equus caballus, kept under extensive management. Subjects were 10 adult mares 5-18 years old that had known each other since birth, and a stallion introduced into the group for breeding for the first time. Kinship coefficient and dominance rank were the most important factors affecting affiliative relationships. Bonds were reciprocal and stronger among mares with higher kinship. Mares spent more time in proximity to close-ranking and lower-ranking females. Mares with stronger affiliative relationships or higher relatedness were not less aggressive towards each other. Affiliative relationships between the stallion and the mares were not reciprocal: lower-ranking mares formed stronger bonds with the stallion but he preferred the less genetically related mares for proximity. However, the stallion was involved in sexual behaviours more frequently with the mares that were more genetically related to him. These results suggest that kinship beyond close relatives may affect affiliative relationships both among familiar and among unfamiliar horses. However, the influence of kinship does not imply that horses possess a kin recognition system and alternative explanations are discussed.

Abstract: Performance of horses, whether in sports or in leisure, depends on both physical abilities as well as temperament. The aim of the present work was to measure individual variation and consistency of behavioural variables, related to temperament, in young horses of the same breed and age, and reared under controlled housing conditions and management. A total of 41 Dutch Warmblood horses were tested at 9, 10, 21 and 22 months of age in two behavioural tests, i.e. the novel object test and the handling test. In the novel object test horses were confronted with an open umbrella that was lowered from the ceiling. In the handling test horses were led by a human to cross a bridge. Per test, behavioural variables in the following behavioural classes were observed: locomotor activity, latency times, postural expressions and vocalisations. Within years, all behavioural variables in the handling test, and all but two in the novel object test were positively correlated (0.36<Rs<0.81, P<0.05). For both tests, at 9, 10, 21 and 22 months of age, a principal component analysis (PCA) was carried out to examine whether there were indications for underlying components of these individual behavioural variables that could possibly serve as measures for temperamental traits. The first component in the novel object test could be regarded as `flightiness' and the second as `sensitiveness'. In the handling test, the first component was suggested to relate to `patience', the second component to `willingness to perform'. The temperamental trait `flightiness' (novel object test) as well as the temperamental trait `patience' (handling test) were positively correlated within both years (0.36<Rs<0.65, P<0.05). For the traits `sensitiveness' (novel object test) and `willingness to perform' (handling test) a positive correlation was only found within the first year (0.44<Rs<0.57, P<0.01). A few individual behavioural variables showed consistency over years. Additionally, just one out of four temperamental traits, namely `flightiness', proved to be consistent over years (Rs=0.49, P<0.01). The temperamental trait `patience' showed a trend between years (Rs=0.31, 0.05<P<0.1). It is concluded that the behavioural tests employed in the present study can be used to reliably identify individual behavioural variables and temperamental traits in young horses. Long-term consistency, i.e. between subsequent years, could not be demonstrated convincingly. Nevertheless, future work may indicate that employing the same approach and considering an even longer time period or different phases of the horse's life, long-term consistency does exist.