The effects of long-term cognitive training on the behaviour and welfare of goats

Within animal husbandry, the biological needs of animals are rarely met. Captive housing environments are often barren and provide animals only with the basic requirements. The introduction of cognitively challenging tasks has been suggested to put captive animals in a position where they can engage evolved cognitive skills and actively control some aspects of their environment. Current evidence suggests that frequent exposure to cognitive stimulation not only constitutes a need, but also has potential positive effects on the welfare of animals. First results indicate that by increasing behavioural flexibility and reducing stress reactivity, cognitive stimulation could improve an animal’s ability to adapt and cope with its environment. The introduction of automated cognitive enrichment devices in the housing environment of animals has been commonly used to provide cognitive stimulation to animals in captivity. Cognitive tests are increasingly conducted in many zoos as well as research facilities around the world to assess cognitive skills of many species. While the goal of cognitive enrichment devices is the engagement of cognitive skills, cognitive tests primarily aim to assess these. Cognitive tests often require animals to be isolated, handled by a human and/or given food reinforcement by a human. To assess the effects of cognitive testing on welfare, it has to be disentangled from these confounding factors (Chapter I). In this thesis, it was investigated whether goats want to be cognitively challenged and whether cognitive stimulation, by means of long-term exposure to cognitive tests, might positively affect behaviour and welfare. Goats are a good model species for this research question because lots of literature on their cognitive skills and their reaction to stress exists. For instance, genetic selection for certain traits such as high productivity can lead to reduced motivation to work for feed as well as reduced activity and stress reactivity. To account for this fact and to increase external validity and variability of our results, dairy goats selected for high productivity, and dwarf goats, not selected for production traits were tested. The first aim of this thesis was to assess whether goats have an intrinsic motivation for cognitive stimulation and thus work for food in a manipulation task that resembles their natural foraging behaviours and requires low effort (Chapter II). We examined whether domestic goats choose to open a sliding door to receive a reward rather than getting the same reward for free. This phenomenon, known as Contrafreeloading (CFL), has been explained by an intrinsic motivation to search for information, novelty, and challenges, amongst other things. Using an Item Response Tree generalized linear mixed model, we found that goats do work for food. Both selection lines of goats are similarly motivated to do so but differ in their performance over several trials. Farm animals must be able to deal with many stressors such as isolation or handling by humans. To investigate if cognitive stimulation has the potential to improve an animal’s ability to cope with these stressors and thus to reduce stress reactivity, we conditioned three treatment groups (Chapter III). Goats from the COG treatment group were tested individually in human-presented object-choice tests. Goats in the POS treatment were isolated individually in the same arena as COG goats but received rewards without being administered the object-choice tests. Goats in the ISO treatment group were isolated individually but neither received a reward nor were administered the tests. Subsequently, we tested all treatment groups in four tests: a Novel Arena test (NA), a Novel Object test (NO), a Novel Human test (NH) and a weighing test (WH) where goats were handled on a weigh scale. To increase external validity, we tested both selection lines (dairy and dwarf goats) at two research sites. We did not find evidence that long-term cognitive testing did have a substantial effect on stress reactivity in any of these tests. However, positive human contact seemed to increase boldness towards a novel object and increased reactivity towards handling in dwarf goats. Furthermore, we found that reactivity towards different stressors is strongly affected by selection line. As farm animals are exposed to different husbandry systems throughout their life, they need to be able to flexibly adapt to their surroundings. It has been proposed that mastering tasks successfully makes the animal proficient in manipulating its environment, and likely improves behavioural flexibility. Using the same three treatment groups as in Chapter III, we investigated whether cognitive testing improves behavioural flexibility of goats in two conceptually different cognitive tests, namely a spatial A-not-B detour test and an instrumental problem-solving test (Chapter IV). Again, we tested both selection lines (dairy and dwarf goats) at two research sites. We found that cognitive testing per se (COG) and exposure to a testing environment via human-given object-choice tests (POS) do not notably affect the performance in subsequent conceptually different cognitive tests in goats. In summary, we found that two different selection lines of domestic goats are similarly interested in cognitive stimulation and are willing to work for it. Further, we did not find general effects of cognitive testing (COG) per se or human-animal-interaction (POS) on responses to different stressors in goats in a novel arena test, a novel object test, a novel human test and during weighing on a scales. Selection lines did differ in some aspects of stress reactivity, but cognitive testing and positive human contact seem to have caused some differences to disappear in the POS and COG dwarf goats. With respect to the goats’ detour or problem-solving performance, we found only subtle differences between treatments. Finally, our multi-lab approach in Chapter III and IV allowed us to detect large variances between research sites that should be considered when making claims from data obtained on single sites