Simple SummaryAs more and more horses are being kept in group housing, it is important to take the horses’ likes and dislikes of other group members (their social bonds) into account to ensure the animals’ well-being and minimise aggressive encounters between group members. Methods for the analysis of social bonds need to be improved and integrated into horse welfare protocols. We observed social behaviour and spatial proximity in 145 feral horses, comprising five groups of Przewalski’s horses and six groups of feral horses. We found that 15 h of observation per group provided robust and reliable data for the analysis of social bonds. Either a combination of counts of friendly approaches and mutual grooming between pairs of horses, or the analysis of the horses’ nearest neighbors through measurements of the animals spatial proximity, are suitable ways of gaining insight into the horses’ social relationships.AbstractSocial bond analysis is of major importance for the evaluation of social relationships in group housed horses. However, in equine behaviour literature, studies on social bond analysis are inconsistent. Mutual grooming (horses standing side by side and gently nipping, nuzzling, or rubbing each other), affiliative approaches (horses approaching each other and staying within one body length), and measurements of spatial proximity (horses standing with body contact or within two horse-lengths) are commonly used. In the present study, we assessed which of the three parameters is most suitable for social bond analysis in horses, and whether social bonds are affected by individual and group factors. We observed social behaviour and spatial proximity in 145 feral horses, five groups of Przewalski’s horses (N = 36), and six groups of feral horses (N = 109) for 15 h per group, on three days within one week. We found grooming, friendly approaches, and spatial proximity to be robust parameters, as their correlation was affected only by the animals’ sex (GLMM: N = 145, SE = 0.001, t = −2.7, p = 0.008) and the group size (GLMM: N = 145, SE < 0.001, t = 4.255, p < 0.001), but not by the horse breed, the aggression ratio, the social rank, the group, the group composition, and the individuals themselves. Our results show a trend for a correspondence between all three parameters (GLMM: N = 145, SE = 0.004, t = 1.95, p = 0.053), a strong correspondence between mutual grooming and friendly approaches (GLMM: N = 145, SE = 0.021, t = 3.922, p < 0.001), and a weak correspondence between mutual grooming and spatial proximity (GLMM: N = 145, SE = 0.04, t = 1.15, p = 0.25). We therefore suggest either using a combination of the proactive behaviour counts mutual grooming and friendly approaches, or using measurements of close spatial proximity, for the analysis of social bonds in horses within a limited time frame.

The maintenance and development of conservation areas by grazing of large herbivores, such as Przewalski's horses, is common practice. Several nature conservation areas house male bachelor groups of this species. When males are needed for breeding they are removed from the groups, often without considering group compositions and individual social positions. However, alpha animals are needed for ensuring group stability and decision making in potentially dangerous situations in several species. To investigate the role of the alpha male in a bachelor group, we observed the behaviour of five Przewalski's horse males during the enlargement of their enclosure. We analyzed the group's social structure and movement orders, as well as the animals' connectedness, activity budgets, and whether they moved with preferred group members and how factors such as social rank influenced the horses' behaviour. We also investigated the excretion of glucocorticoid metabolites (GCM) via faeces of the horses while exploring a new area as a parameter of glucocorticoid production. Our results show that the alpha male is important for a bachelor group in changing environmental conditions. The alpha male had the highest level of connectedness within the group. When exploring the new environment, its position in the group changed from previously being the last to being the first. Furthermore the whole group behaviour changed when exploring the new area. The stallions showed reduced resting behavior, increased feeding and did not stay close to each other. We found that the excretion of glucocorticoid metabolites of most horses rose only marginally during the first days on the new area while only the alpha male showed a significant increased amount of glucocorticoid production during the first day of the enclosure enlargement.

Les ruminants ont la faculté de synthétiser toutes les vitamines B et K dans leur rumen ; par ailleurs, le pâturage leur fournit en abondance des carotènes (pro-vitamines A) et de la vitamine E alors que l’ensoleillement direct ou par l’intermédiaire du foin assure un bon approvisionnement en vitamine D. Traditionnellement, les risques de déficiences se limitaient principalement à la vitamine A en fin d’hiver. Mais à présent, l’intensification des productions animales, l’évolution des modes d’élevage et d’alimentation, les plus grandes exigences concernant la santé et la qualité des productions, imposent de prévoir des supplémentations étendues relatives à l’ensemble des vitamines liposolubles et même à certaines vitamines B en tenant compte d’indications particulières telles que fertilité (A), immunité (A, E), prévention des rétentions placentaires et des myodystrophies (E et Se), des hypocalcémies puerpérales (D), de la Nécrose du cortex cérébral lors d’acidose ruminale (Bl). stimulation de la microflore digestive et lutte contre la cétose (PP).