Publication Database

First insights of moment-to-moment decisions in a Small World: new multi-choice system with eight ecologically meaningful resources to assess rats’ daily choices and decisions (2025)

Art

Hochschulschrift

Autor

Puls, Fiona (WE 11)

Quelle

Berlin, 2025 — V, 76 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/49304

Kontakt

Institut für Tierschutz, Tierverhalten und Versuchstierkunde

Königsweg 67
14163 Berlin
+49 30 838 61146
tierschutz@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Understanding what animals want is essential, as it reflects their behavioural mechanisms and needs – particularly interesting in the context of animal welfare. However, studying animal decisions is challenging because the animals cannot just be asked for their preferences. While previous studies have primarily focused on studying animals’ choices and preferences for specific resources, they have rarely examined daily decisions. This study introduces a novel testing system, the SW, which optimises and extends prior-choice tests in various ways: Choices between eight simultaneously offered ecologically relevant resources are provided in a long-term test to study everyday moment-to-moment decisions with the example species of rats (Long Evans, Rattus norvegicus). Each of the 11 rats is once used as focus rat for ten consecutive days, whereas the other 1-2 sister/s serve as social partners. The SW system consists of a CCC connected via plastic tubes to eight resource cages. These cages provide a quasi-natural environment including resources for basic survival (food, water, hiding/resting), resources for more specific needs (running wheel, sand bath) and resources of additional ecologically relevant stimuli (predator odour, novel object, restricted contact to social partners). Movement sensors are installed at the entrances and exits of the resource cages so that data of the daily frequencies, durations and sequences of visits, as well as for the decisions and choices of the various resources is collected automatically. The “choices” are defined as the duration between the time of entry to a resource cage and the entry into the next resource cage. The “decisions” refer to the duration between the exit from one and the entry into the next resource cage. The data are analysed using generalised mixed-effects models including survival modelling for multiple states. Results show that the general activity decreases from day 1 to 2 and remains on a constant level throughout the experimental phase. Rats visit all resource cages at least once per day throughout the experiment. The frequency of resource use is relatively high in the RWC, NMC, SPC; intermediate in the FIC and WIC and lowest in the POC, NOC and DAC. The daily duration of resource use remains relatively stable across the experiment but vary across the different resource types. The NMC constantly shows high duration of use, while POC, NOC and DAC have constantly low durations with peaks on days when stimuli are renewed (e.g. fresh predator odour, a new novel object, or treats in the sand bath). The most frequent transitions occur between the RWC, WIC, FIC, and SPC. The frequency and duration of the visits do not necessarily reflect the importance of the resources. As depending on the need, a short visit e.g. to the WIC, may be sufficient to satisfy the animals' need to drink. Nevertheless, the fact that all resources are visited daily suggests that each holds relevance for the animals. The study also evaluates whether the experimental system induces stress. Potential stressors include the novelty of the experimental system and resources, spatial and social restrictions, and the limited food choice. Stress is measured non-invasively via FCM measurement. The mean FCM concentration decreases slightly when the rats are transferred from the housing cage to the experimental system and slightly increases when they are returned to their housing cage. Furthermore, the rats quickly acclimatise to the experimental system, as constant activity can be measured from day 2 onwards. Overall, the SW system enables an effective method to assess simultaneously multiple resources through different indicators. Due to the possibility of representing the decisions and choices of the animals with different measurement methods, this system represents an extension of previous multi-choice tests. It is sufficiently sensitive to detect even small environmental changes and enables the collection of data on multifaceted aspects of resource use. To further investigate the importance of the resources for the animals adding an obstacle for reaching the resources will be advantageous (e.g. by adding distances between the resources). Moreover, the external validity of the approach can easily be extended by e.g. testing groups of animals and using animals of a variety of species, ages or sexes.