Abstract: Abstract Horses are kept in various housing systems, for example, with conspecifics in horse pens or singly in horseboxes, with or without pasturing. To provide appropriate living conditions for horses, it is necessary to know in which conditions they feel well or unwell. Here, a cognitive bias assessment provides information about an individual's affective state and its well-being. When a positive affective state prevails, animals tend to judge optimistically in ambiguous situations. When a negative affective state prevails, animals judge pessimistically in unclear situations. In the present study, we trained horses on a spatial discrimination task and evaluated their judgment of ambiguous locations when they had access to pastures and contact to conspecifics versus when they were kept singly in horseboxes. Ten days of pasturing and contact with conspecifics after being kept singly in horseboxes for 6 months induced a positive cognitive bias in the horses. We suggest that horses need to act out certain behaviors like exploration, social interaction, play, or grooming to fulfill their needs. After a time in which they were individually in horseboxes without pasturing and access to the herd, they seem to have a positive cognitive bias once they have access to pastures and conspecifics. This positive cognitive bias effect seems to disappear over time, as horses appear to adapt to the circumstances.

Abstract: Both white-tailed deer, Odocoileus virginianus, and mule deer, O. hemionus, females defend fawns against coyotes, Canis latrans, but only mule deer defend nonoffspring conspecific and heterospecific fawns. During a predator attack, females may have to decide whether to defend a fawn while having imperfect information on its identity obtained from hearing a few distress calls. Although imperfect recognition can influence altruistic behaviour, few empirical studies have considered this point when testing functional explanations for altruism. We designed a series of playback experiments with fawn distress calls to test alternative hypotheses (by-product of parental care, kin selection, reciprocal altruism) for the mule deer's defence of nonoffspring, specifically allowing for the possibility that females mistake these fawns for their own. White-tailed deer females approached the speaker only when distress calls of white-tailed deer fawns were played and when their own fawn was hidden, suggesting that fawn defence was strictly a matter of parental care in this species. In contrast, mule deer females responded similarly and strongly, regardless of the caller's identity, the female's reproductive state (mother or nonmother) or the presence of their own offspring. The failure of mule deer females to adjust their responses to these conditions suggests that they do not defend nonoffspring because they mistake them for their own fawns. The lack of behavioural discrimination also suggests that kin selection, reciprocal altruism and defence of the offspring's area are unlikely to explain the mule deer's defence of nonoffspring. We identify causal and functional questions that still need to be addressed to understand why mule deer defend fawns so indiscriminately.

Abstract: The use of secondary reinforcement is widely accepted to support operant learning in animals. In farm animals, however, the efficacy of secondary reinforcement has up to now been studied systematically only in horses (“clicker training”), and the results are controversial. We investigated the impact of acoustical secondary reinforcement on voluntary, self-controlled visual discrimination learning of two-dimensional shapes in group-housed dwarf goats (Capra hircus). Learning tests were conducted applying a computer-controlled learning device that was integrated in the animals' home pen. Shapes were presented on a TFT-screen using a four-choice design. Drinking water was used as primary reinforcement. In the control group (Gcontrol, n = 5) animals received only primary reinforcement, whereas in the sound group (Gsound, n = 6) animals got additional acoustical secondary reinforcement. Testing recall of shapes which had been successfully learned by the goats 6 weeks earlier (T1), we found a weak impact of secondary reinforcement on daily learning success (P = 0.07), but not on the number of trials the animals needed to reach the learning criterion (trials to criterion, n.s.). Results in T1 indicated that dwarf goats did not instantly recall previously learned shapes, but, re-learned within 250-450 trials. When learning a set of new shapes (T2), there was a strong influence of secondary reinforcement on daily learning success and on trials to criterion. Animals in Gsound reached the learning criterion earlier (P < 0.05) and needed fewer trials (1320 versus 3700; P < 0.01), compared to animals in Gcontrol. Results suggest that acoustical secondary reinforcement supports visual discrimination learning of dwarf goats, especially when the task is new and the salience of S+ is low.

Abstract: Forty-four horses were used to determine if a learned stimulus could be used to increase acquisition of a response unrelated to the original learned task. Horses were paired by age, breed and sex. One randomly chosen horse from each pair served as the control while the remaining horse was trained to respond to a visual stimulus by pushing a lever to obtain a food reward. In Experiment I (n=28), the food reward was delivered in a feed box located equidistant between two levers located 2.7 m apart on one wall of the test stall. Trained horses were given 30 training trials daily until they achieved at least 85% correct responses in three nonconsecutive days. After each trained horse reached criterion, both horses in the pair were tested in 30 trials daily for five consecutive days in a modified Y maze. The stimulus that indicated the correct lever in the initial training task was used to signify the correct arm of the maze for both the control and trained horses. The correct arm of the maze was changed randomly during each daily session, and correct choices resulted in a food reward. In Experiment II (n=16), levers were located on opposite walls (11 m apart) of the test stall, and the stimulus and modified Y maze were simplified. Trained horses received 15 training trials daily until they reached at least 85% correct responses on three consecutive days. As each trained horse achieved this criterion, both horses in the pair were tested in a maze for 15 trials daily for 7 days. Again, the stimulus from initial lever-pressing task was used to signify the rewarded arm of the maze. Correct choices of trained and control horses in both experiments were compared using a paired t-test. In Experiment I, no differences (P>0.34) in mean correct responses were detected between trained and control horses on the first day in the maze (15.3 and 16.8, respectively) or after 5 days in the maze (84.0 and 82.1, respectively). Similarly, in Experiment II, trained and control horses did not differ (P>0.50) in mean correct responses on the first day (6.9 and 7.4, respectively) or after 7 days in the maze (63.6 and 61.6, respectively). These results indicate that the stimuli used to solve the lever-pressing task were not utilized by horses in the maze task, and that horses may have difficulty transferring learned visual stimuli to new tasks.

Abstract: Social recognition among familiar unrelated lambs was assessed in a series of tests. Lambs and their mothers were housed together in small groups for 1 week (Original groups; O) then reorganized into new groupings (Recent-groups; R) for the remainder of the experiment. During test series 1, lambs that were paired with a familiar O-group partner, from which they had been separated for 5 days, emitted fewer distress bleats than did those tested with an unfamiliar partner. This same effect was not evident when the test was repeated several hours later, indicating that the animals had become habituated to the testing procedures. Two days later, when given the choice between an O- versus a R-partner (test series 2), lambs did not display a preference for either of the stimulus lambs. However, in an additional two-choice test (test series 3) the subject lambs responded discriminatively to a recent familiar partner that was simultaneously present with an unfamiliar lamb. Overall, the results suggest that lambs are capable of developing discriminative relationships with age-mates from different sub-groups, and that such social discrimination persists over a separation period lasting at least several days. It is not clear whether lambs recognize several individual conspecifics per se or discriminate between members of higher order social categories (e.g. familiar versus unfamiliar individuals). Proximal and distal social discrimination may be mediated by different combinations of sensory modalities.