Behavioral effects of floor pens as environmental enrichment for laboratory rabbits (Oryctolagus cuniculus)

Laboratory animals are indispensable for science, particularly in biomedical research. Their welfare must meet their physical, social and physiological needs. Ethological evaluations are crucial for identifying and correcting abnormal behaviors caused by captivity, often through tools like environmental enrichment (EE). This study evaluated the behavioral effects of implementing floor pens as EE for individually caged laboratory rabbits. A single observer analyzed the behavior of 24 male adult rabbits inside the cages (48 ×80 x 60 cm) before the EE application through all-sample observations over two months. After, the test group (n = 15) was introduced to large floor pens (120 ×180 cm; no ceiling) once a week for two months, with 60 s all-sample observations every 10 minutes. The control group (n = 9) was not introduced to the EE. After this period, all animals were observed once again inside the cages, in order to compare behavioral frequencies before and after the EE application using appropriate statistical tests. The test group showed increased inactivity (31.1 vs. 55.4 %; Student's t-test, t = - 9.34, p < 0.001) and a significant decrease in negative behaviors (13.5 vs. <5 %; Wilcoxon test, V = 119, p < 0.001) after the EE application. Both behavioral categories frequencies aligned more closely to values reported in other related studies. Inside the floor pens, rabbits expressed locomotory, exploratory and positive behaviors for a great portion of time (more than 80 % of total time). These findings highlight the effectiveness of implementing floor pens as EE in reducing negative behaviors, increasing daytime inactivity, and promoting exploration and positive welfare of laboratory rabbits.