Abstract: The design of a captive environment should facilitate the expression of the natural behavioural repertoire of the species concerned. The domestic horse (Equus caballus) is a social, herd dwelling species that is often housed in isolation from con-specifics or kept in groups in paddock enclosures. Although the latter allows for social interaction and does not restrict movement per se, it may not promote natural activity patterns or group cohesion. The aim of the current study was to assess the impact of two different paddock designs on the behaviour of a stable group of horses (n=6: 2 mares, 4 geldings).
The paddock designs tested were adjacent and grassed similarly, but configured differently. A central paddock (75 x 75m) designated NT, was surrounded by a track 1.6-5.5m wide, designated T. The horses were turned out in their group into T or NT for 3 consecutive days. Their behaviour was recorded for one hour three times each day (10.00, 13.00, 16.00 hrs). Within each observation period of one hour focal sampling was used, each individual horse being observed for a 10 minute period. They were then moved to the other enclosure type for a further 3 consecutive days, followed by a repeat of each condition. When turned out the horses were fitted with a global positioning system device (Garmin Forerunner 305) to monitor distance travelled and speed for the period 10.00-17.00 hrs. The mean percentage of time spent in each behavioural state (standing alert, standing resting, walk/trot, grazing, lying, social interaction) during the periods observed was calculated. Behaviour during social interactions was classified as either affiliative (approach, follow, friendly contacts, mutual grooming) or agonistic (approach and retreat, bite, chase, head threat).
The horses travelled significantly further in T than in NT (paired samples t-test: t (5) = 11.74, p<0.001) and moved significantly faster (Wilcoxon signed rank test: z = -2.21, p=0.03). See Table 1. When the percentage of time spent in each behavioural state in T and NT was compared some significant differences were found. A significantly higher percentage of time was spent active (walking /trotting) in T than in NT (paired samples t-test: t (5) = 5.74, p=0.002). Standing alert was only recorded in T (paired samples t-test: t (5) = 3.48, p=0.02). A significantly higher percentage of time was spent grazing in NT than in T (paired samples t-test: t (5) = -3.58, p=0.016). Significantly more social interaction occurred in T than in NT (paired samples t-test: t (5) = 5.93, p=0.002). See Figure 1. In T, 91% of social interactions were affiliative and 9% agonistic, whereas in NT 29% were affiliative and 71% agonistic. No difference was found in the percentage of time spent standing resting or lying down in T and NT.
The benefits of housing horses in groups as opposed to individually have been demonstrated in previous studies. In addition to better satisfying the behavioural needs of the horse it has been found that group housed horses adapt more easily to training and display less undesirable behaviour than those housed individually (Rivera et al. 2002; Søndergaard and Ladewig 2004; Visser et al. 2008). However, individual housing is frequently selected by horse owners in preference to group housing to avoid the risk of injury during agonistic encounters. Fureix et al. (2012) suggest that management practices may well contribute to aggressiveness in horses and that the conditions under which we keep horses should be reviewed. The findings of the present study indicate that the design of the enclosure in which groups of horses are kept affects the nature of social interactions. The T paddock design resulted in reduced intra-group aggression. However, this paddock design also reduced the time spent grazing and increased vigilant behaviour. Although the results demonstrate that a paddock system including tracks may facilitate group cohesion and more natural movement patterns, the long-term impact on behaviour and welfare requires further investigation.
References:
Fureix C, Bourjade M, Henry S, Sankey C, Hausberger M. (2012). Exploring aggression regulation in managed groups of horses (Equus caballus). Applied Animal Behaviour Science 138: 216-228.
Rivera E, Benjamin S, Nielsen B, Shelle J, Zanella AJ. (2002). Behavioural and physiological response of horses to initial training: the comparison between pastured versus stalled horses. Applied Animal Behaviour Science 78: 235–252.
Søndergaard E, Ladewig J. (2004). Group housing exerts a positive effect on the behaviour of young horses during training. Applied Animal Behaviour Science 87: 105-118.

Abstract: It is a common practice that the domestic horse mare is removed from her home environment and transported elsewhere for mating. After conceiving she is returned back into her home environment and social group, containing often familiar stallions and geldings. If we presume that the behavioural adaptation for infanticide relevant for wild, or free-ranging horses has not be lost in domestication (and it is clear that it remains at least within feral populations), then we may expect that, unless prevented by fencing or other management measures, the dominant males in the home social group may subsequently attempt infanticide. Foetal loss is a common phenomenon in domestic horses, being usually substantially higher than that in other domestic ungulates reaching up to 40%. One adaptive response to infanticide risk in polygynous populations is the Bruce effect. Pregnant females terminate their pregnancies when exposed to a dominant strange male. Our previous studies on plain zebra suggested the possibility of the Bruce effect also in equids. In this study we therefore tested the presumption that the Bruce effect could explain foetal loss in domestic horses. Based on reproduction records from horse breeders, we have recently published that bringing a pregnant mare which had been mated away from home into a vicinity of a familiar male who was not the father of her foetus increased probability of pregnancy disruption (Behav Ecol Sociobiol DOI: 10.1007/s00265-011-1166-6). These mares aborted in 31% of cases, while none of those mated within the home stable aborted. Repeated sexual activity either by a stallion or dominant gelding from the normal home group was observed shortly after the mare came from away-mating. Pregnant mares isolated from home males by a fence were even seen soliciting them over the fence. Therefore, there is probably some other mechanism than the Bruce effect leading to pregnancy block in the mare. We speculate that, once returned to the home “herd”, and introduced to familiar males, mares were more likely to terminate their pregnancy to save energy and avoid likely future infanticidal loss of their progeny by dominant male(s) of the home social group. Additional data has now showed that if a mare was mated away from home and was brought into an environment containing mares only, she was less likely to abort than a mare returning to an environment containing familiar male or males. This further supports our above hypothesis. Supported by AWIN, EU FP7 project No. 266213.

Abstract: Horses provide an interesting animal model to test short- and long-term effects of the paternal influence on the offspring under natural conditions. As a highly social animal, horse naturally is living in long-term harem groups building strong familiar bonds. Arguing that the environment of a juvenile is highly important for the development of cognitive and social functions as well as for the emotional competence, a future study on domestic horses wants to highlight the paternal influence on the offspring as well as special effects of the stallion during the first two years of the foals´ life. Nowadays, in most husbandry systems it is still common to keep the stallions separated, raising the offspring in an intact harem group is very rare. The aim of this study is to describe the role of the stallion in the early development of the foal in an extensive pasture management system living in natural harem groups. Results are going to be compared to findings of studies on groups without the male present in the rearing phase. A precise behavioural analysis is planned; direct behavioural observations are going to be supported by long-term and continuously activity measures by special telemetry collar systems. Additional physiological measures should give evidence of the investment of the stallion. The young horses will be confronted with different tests of cognitive and social abilities (exploration behaviour, fear behaviour, play behaviour). The results of this study will contribute to fundamental research in the behaviour of the horse and might display an important step to animal welfare in modern horse husbandry. It will be possible to set a time-frame in which the male does have positive influence on the offspring and therefore should be kept with the family. A detailed knowledge of the influence of the male to cognitive and social abilities could as well be applicable in the training of horses and therefore be of great importance in equestrian sports.