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Cage size and enrichment effects on the bone quality and fluctuating asymmetry of fattening rabbits

Journal Contribution - Journal Article

We studied the effect of increased cage size on different aspects of bone
quality (bone strength, diameter, weight and length) and fluctuating asymmetry (FA). Such characteristics may indicate improved animal welfare, as greater bone quality may decrease fracture incidence during handling, whereas decreased FA has been suggested to signal decreased stress. As stress is likely not only influenced by the quantity of space but also by its quality, we also studied the effect of environmental enrichment. Groups of 8 rabbits were housed in wire open-top cages of 0.40, 0.46, 0.53, 0.64, 0.80, 1.07 and 1.60 m2 from weaning till slaughter. All cages of 0.40 and 0.46 m2 (12 cages/size) were left barren to allow sufficient mobility. Half of the larger cages were enriched with a wooden enrichment structure that could be used to gnaw on, hide in, or lie in (6 cages per size × enrichment treatment). Increased cage size led to an increase in tibiofibula diameter (P = 0.008), a tendency for increased tibiofibula weight (P = 0.051), and decreased FA (P = 0.010) suggesting improved welfare. Bone length and strength were not affected by cage size (P > 0.1). Enrichment did not affect FA (P > 0.1), in contrast with our expectations based on previous glucocorticoid
analysis. This discrepancy between indicators may be due to sensitivity to other types of stressors, or due to different sensitive periods. In summary, rabbits housed in larger cages had wider, heavier bones, but the absence of changes in bone strength indicate that this is unlikely to result in a decreased fracture incidence. In larger cages FA was lower, suggesting a favorable effect on welfare, whereas no effect of enrichment was shown.
Journal: Journal of Animal Science
ISSN: 0021-8812
Volume: 90
Pages: 3568–3573
Publication year:2012