Abstract: This study has shown that domestic horses are capable of cross-modal recognition of familiar humans. It was demonstrated that horses are able to discriminate between the voices of a familiar and an unfamiliar human without seeing or smelling them at the same moment. Conversely, they were able to discriminate the same persons when only exposed to their visual and olfactory cues, without being stimulated by their voices. A cross-modal expectancy violation setup was employed; subjects were exposed both to trials with incongruent auditory and visual/olfactory identity cues and trials with congruent cues. It was found that subjects responded more quickly, longer and more often in incongruent trials, exhibiting heightened interest in unmatched cues of identity. This suggests that the equine brain is able to integrate multisensory identity cues from a familiar human into a person representation that allows the brain, when deprived of one or two senses, to maintain recognition of this person.

Abstract: Horses are a highly social species living in complex social systems which should require them to memorise and generalise social experiences and distinguish between familiar and unfamiliar conspecifics. In the main part of my thesis I concentrated on the specific conflict situation of a horse being introduced into a new social group, and investigated its behaviour and stress level. Horses were either introduced (1) immediately, (2) after an observation period, or (3) together with an integration horse after an observation period. Additionally, in the second part of my thesis I arranged several experiments to elaborate additional aspects which could affect the behaviour of horses during introductions. In this study I could describe a simplified method for measuring stress through the analysis of faecal GCMs in horses. An enzyme immunoassay (EIA) for 11-oxoaetiocholanolone using 11-oxoaetiocholanolone-17-CMO: BSA (3?,11-oxo-A EIA) as antigen showed high amounts of immunoreactive substances. The new assay increases the accuracy of the test and lowers the expenses per sample; also storing of samples at room temperature after collection is less critical. This is a big advantage both in the field of wildlife management of equids and in the field of equestrian sports (chapter 1). Comparing the different introduction techniques, the introduction with an integration horse led to significantly less total interactions and lower levels of aggression than the introduction of single horses, both immediately and after several days of observing the new group. Additionally, by observing the behaviour of the horses during everyday sociality I could develop a formula describing the interrelationship between expected aggression level and enclosure size per horse. The curve takes an exponential shape. Starting from a space allowance of 300 m2 and more per horse, the amount of aggressions per hour approaches zero. For the reduction of aggression levels and injury risks in socially kept horses I recommend an enclosure size of at least 300 m2 per horse (chapter 2). I further investigated the stress level of the introduced animals. Horses which were immediately introduced did not show elevated faecal GCMs. In contrast, horses which were introduced after an observation period had slightly elevated values 2 and 3 days after the introduction. For horses introduced together with an integration horse faecal GCMs were significantly above the baseline value on the day of introduction and 1 day after it. These differences between introduction techniques indicate that the introduction event itself is not as stressful as previously assumed. Rather standing together with an integration horse and not being able to integrate immediately into the complete group elicits stress in horses (chapter 3). In the commentary of chapter 4 several studies are discussed which failed to demonstrate social learning in horses. It is argued that they did not consider important aspects which could have an influence, such as the dominance status or the social background of the horses (chapter 4). In chapter 5 a social feeding situation was investigated. The social rank as well as the position of conspecifics affected the feeding strategy of horses. Domestic horses used social cognition and strategic decision making in order to decide where to feed. When possible they tended to return to the same, continuously supplied feeding site and switched to an ?avoidance tendency? in the presence of dominant horses or when another horse was already feeding there (chapter 5). One possibility to recognize group members is through olfactory recognition. In chapter 6 it is shown that horses are able to distinguish their own from their conspecifics? faeces. In addition, they paid most attention to the faeces of those group members from which they received the highest amount of aggressive behaviour (chapter 6). Horses show cognitive abilities because they are able to use humans as local enhancement cues when searching for food, independently of their body posture or gaze consistency when the persons face them. Moreover, they seem to orientate on the attention of familiar persons more than of unfamiliar persons (chapter 7). Altogether, the results of this thesis provide further support for the view that horses show good conflict resolution strategies. They are perfectly able to deal with the conflict situation of being introduced to new group members, and the introduction event itself is not as stressful as previously assumed. It is rather suggested that standing together with an integration horse and not being able to integrate immediately into the complete group elicits stress in horses. All additional experimental set-ups could demonstrate that horses are well capable of social cognition.

Abstract: Ziel: Überprüfung der Tiergerechtheit von in der Bauweise unterschiedlichen
Futterabrufstationen für Pferde in Gruppenhaltung anhand ethologischer
und physiologischer Parameter. Material und Methoden: In 32
Offenlaufställen (452 Pferde) mit computergesteuerten Abrufstationen
für Kraftfutter und Heu erfolgten kontinuierliche Direktbeobachtungen
für je einen 24-Stunden-Tag (Tortenstückverfahren). Erfasst wurden: Aufenthaltsdauer,
Besuchshäufigkeit, Droh- und Meideverhalten im Fütterungsbereich,
Blockaden sowie Herzfrequenz und Integumentverletzungen.
Ergebnisse: Eine Durchlaufstation reduzierte die Zahl der Auseinandersetzungen
im Fütterungsbereich signifikant. Ansonsten erhöhten die
für das fressende Pferd tiergerechten Varianten (Fressstand mit Eingangssperre,
ohne Austreibehilfe) Besuchshäufigkeit und Aufenthaltsdauer und
steigerten somit auch die Anzahl an Drohgesten je Tier und Tag. Insgesamt
betrachtet kann jedoch die Anzahl an sozionegativen Interaktionen
im Fütterungsbereich der Abrufstationen als relativ gering eingestuft
werden. Die Herzfrequenz lag im Warteareal bei den meisten Pferden im
physiologischen Bereich (45,1 ± 12,42 Schläge/min), erhöhte sich jedoch
in der Abrufstation um ca. 20 Schläge/min. Einige Tiere zeigten möglicherweise
stressbedingt kurzfristig auffallend hohe Werte (≥ 100 Schläge/
min). Integumentverletzungen im Zusammenhang mit dem Fütterungssystem
traten nicht auf. Der wichtigste Einflussfaktor auf die Untersuchungskriterien
war der Betrieb (Fläche, Konzeption, Management).
Schlussfolgerung: Durchlaufstationen sind pferdegerechter als Rücklaufstationen.
Nicht tiergerecht sind Stationen mit stromführender Austreibehilfe.
Weitere bauliche Unterschiede der derzeitigen Futterabrufstationen
dürften eher von untergeordneter Bedeutung sein, vor allem da
Flächengebot und Konzeption der Offenstallanlage sowie das Management
die überprüften Kriterien zur Tiergerechtheit maßgeblich beeinflussen.
Untersuchungen zur Abklärung der Ursache für die vereinzelt aufgetretenen
sehr hohen Herzfrequenzwerte sollten durchgeführt werden.
Objective: Comparison with regard to animal welfare of different automatic
feeding systems for hay and concentrate in group housing systems
for horses using parameters of ethology and physiology. Material and
methods: Parameters of research comprised: duration of stay, frequency
of visit, threatening behaviour with and without risk of injury, and avoiding
behaviour as well as heart rate and injuries of the integument. 452
horses were observed at the feeding area of 32 run-out-sheds. Every group
of horses was continuously observed following the pie chart system for
24 hours. Results: The “walk-through” station significantly reduced the
number of conflicts in the feeding area, whereas those systems which are
appropriate for the feeding horses (feeding station with access barrier and
without stimulation device by electric shock) led to a higher frequency of
visits and a longer duration of stay resulting in more threatening gestures.
However, the number of negative interactions in the feeding area of the
feeding systems can all together be classified as relatively insignificant.
The heart rate was within the physiological range (45.1 ± 12.42 beats/min)
in the waiting area, but increased by approximately 20 beats/min on average
within the feeding station. Some horses showed a very high heart rate
(≥ 100 beats/min) while entering the feeding station, possibly stress-related.
There were no injuries of the integument associated with the feeding
systems. The most important factor of the observation criteria was the
individual group housing system with its different dimensions, conception
and management. Conclusion: “Walk-through” stations are better than
”walk-back” stations with regard to animal welfare. Likewise, automatic
feeding stations with a current-carrying stimulation device are not supportive
of good welfare. The other differences between the constructions
of feeding stations of present systems are probably of less importance, particularly
as it was shown that the stable (management, stable area, conception)
had a significant influence on the surveyed parameters. Investigations
to obtain information on the cause for the sporadic occurrence of
very high heart rate values should be undertaken.]

Abstract: In order to improve the housing conditions of stallions in individual boxes by offering a possibility to have more social contact, the Swiss national stud farm tested a new box system for horses, allowing increased physical contact with the neighbouring stallion. The aim of this part of the study was to investigate whether this type of housing system (named “social box”) potentially induces a change in stress reactions in stallions compared to conventional boxes. Therefore faecal cortisol metabolite (FCM) concentration was measured as a non-invasive parameter to assess endocrine responses related to this new environment.
Four groups each consisting of eight adult Freiberger breeding stallions were included in the test design. Every stallion spent three weeks in a conventional box and in a social box respectively (cross-over design). The conventional box consisted of a separation wall with a lower opaque part and an upper part with vertical barriers (5 cm between barriers), allowing visual and olfactory contact but strongly limiting tactile contact. The separating wall of the social box consisted of two lateral sections, one part being opaque to the ceiling and the second part consisting of vertical barriers (30 cm between barriers), allowing the horse to have physical contact with its neighbour or to avoid it.
In horses, FCM concentration reflects an average level of circulating cortisol over a period of approximatively 24h. Faecal samples were collected the day following integration in social / conventional boxes, reflecting the potential stress induced by increased social interactions during the integration. In order to asses potential chronical stress, faeces samples were also collected in week one, two and three after the integration into the social / conventional box (in total: 4 samples per horse and housing system). The samples were immediately stored at -20°C until they were analysed. The samples were not analysed in the laboratory until the end of the experiment, therefore the duration of conservation in the freezer varied from 40 to 429 days.
A considerable percentage of data from groups 1 and 2 was below the detection limit (<0.8 ng/g) (Tab. 1). Thus the statistical analysis was conducted with the FCM concentration from groups 3 and 4 (n horses = 16) which contained no values below the detection limit.
Tab. 1: Details about FCM values and storage time for the 4 groups of stallions
Group Storage duration [d] Proportion of data below the detection limit (<0.8 ng/g) Mean [ng/g] Median [ng/g]
Group 1 384-429 55.6 % 2.2 0
Group 2 315-360 25.5 % 5.8 6.3
Group 3 41-79 0.0 % 8.7 8.0
Group 4 40-85 0.0 % 5.8 5.4
Despite the impressive social interactions observed between the stallions directly after being introduced into the social boxes, we did not find any differences in FCM concentration between the stallions being introduced into the conventional box and the social box on the day of integration (social box: n samples = 16, mean±SD: 6.9±4.7 ng/g; conventional box: n samples = 16, mean±SD: 9.0±11.2 ng/g; Wilcoxon signed rank test V = 70, p = 0.94).
Overall the samples taken during integration and in week one, two and three did not show evidence of changes in FCM concentration in either housing system over a longer period of time (social box: n samples = 64, mean±SD: 7.9±6.2 ng/g; conventional box: n samples = 64, mean±SD: 6.6±3.4 ng/g; Linear mixed model (LMM), p = 0.56).
Our results suggest that the possibility of having physical contact with a conspecific does not induce changes in FCM concentration in breeding stallions. The considerable percentage of values below the detection limit in groups 1 and 2 seemed to correlate with the increasing duration of storage before analysis. During the IESM Network Meeting 2015, we would like to discuss possible methodological issues and the possibilities to correctly integrate these low values in the statistical analysis.

Abstract: Aggression can generate anxiety, create uncertainty about its aftermath and jeopardise social relationships. Postconflict interactions serve as conflict management strategies to mitigate these consequences. Whereas postconflict interactions are well characterized in many animals, their functions are still insufficiently investigated. Four functional hypotheses have been proposed: stress reduction, relationship repair, self-protection and benign intent. We aimed to test these hypotheses in females of a tolerant macaque species, the crested macaque, Macaca nigra, under natural conditions, for three postconflict interactions: reconciliation, affiliation and aggression with third parties. Our results provide meaningful contrasts compared with findings in other species. We found no evidence that aggression had consequences for individuals' behavioural indicators of anxiety, although it increased the likelihood of secondary aggression with third parties. There was little evidence for the stress reduction hypothesis as the occurrence of any of the three postconflict interactions investigated had little effect on the measured behavioural indicators of anxiety. Conflict and dyad characteristics also had limited influence on anxiety. The relationship repair function was only partly validated: dyads with stronger bonds or that exchanged more support did not reconcile more often, but dyads with attributes related to the symmetry, stability and predictability (i.e. security) within relationships did. Patterns of initiation and directionality of postconflict interactions in this study population suggest that reconciliation may constitute the signalling of appeasement and benign intent. Furthermore, we found that aggression towards third parties may serve as a source of self-protection and reassertion of the females' social status. The distinctive pattern of postconflict management strategies revealed in wild female crested macaques appears to be related to their typically tolerant social style. These results demonstrate the usefulness of concomitantly studying aggression, postconflict interactions and their functions, to understand conflict management strategies comprehensively, while taking into account the level of social tolerance characterizing the studied society.