Evaluation of environmental enrichment for Xenopus laevis using a preference test

Xenopus laevis frogs have long been widely used as an animal model in research. However, their husbandry has scarcely evolved, although they are prone to environmental stress. Environmental enrichment has been shown to improve animal welfare and adaptation, as well as zootechnical indices, which have become very important in recent years. The aim of this study was to examine the preferences of X. laevis frogs for various elements of environmental enrichment: opaque polyvinyl chloride (PVC) pipes, artificial plants and clear spaces. A preferential study was conducted in two different tanks, each divided into six parts, where the two enrichment elements were rotated. Ten X. laevis frogs were introduced into each tank, and the number of frogs was counted in each division three times per day for six weeks. The number of frogs in the different spaces and different enrichments was evaluated through a Poisson regression model. Frogs preferred plants to PVC pipes and clear spaces regardless of the position of the enrichment element, time and day. This indicates that artificial plants should be used as the enrichment element rather than the commonly used PVC pipes. In addition, the use of plants facilitates the observation of frogs without disturbing them and reduces the accumulation of detritus, as it occurs inside the pipes.