Determining minimal space requirements of group-housed rabbits based on their spatial distribution

E. van Poucke¹, L. Maertens¹, A. van Nuffel¹, J. van den Abeele², L. Lens² and F. Tuyttens¹

¹Agricultural Research Centre, Merelbeke, Belgium
²Department of Biology,University of Ghent, Ghent, Belgium

Commercial housing of fattening rabbits (small groups in small barren wire net cages) constrains the performance of natural behavior and causes severe animal welfare problems. To increase the absolute space available per animal without reducing the stocking density, rabbits could be housed in larger groups. The increased risk of aggression and mortality might be minimized by adjusting pens according to the animals’ needs. To assess the spatial requirements of group housed animals, a new method, based on the ‘critical interindividual distance’, was tested. It hypothesizes animals to distribute homogeneous if the allocated space is too restrictive and heterogeneous if it is not. 14 groups of 22 weaned rabbits housed in pens of 7 sizes (range: 1.32 - 3.27 m²), were studied during the fattening period. To evaluate the effect of environmental enrichment, each pen size was provided in a barren and an enriched (2 erect wooden boards placed next to each other in the centre of the pen) form. Digital photographs were made every 30 min during 48 hours per pen per week. The spatial distribution of the rabbits in the pens was determined by dividing each pen in 4 imaginary identical parts. The number of animals in each part was recorded. A heterogeneity index, based on the standard deviation of this numbers, was calculated. This index increased with pen size (p=0.003) and the presence of enrichment (p<0.0001). Rabbit age negatively affected the index (p<0.0001) but this effect decreased with pen size (p<0.0001) and the absence of enrichment (p=0.004). These results suggest that when housing rabbits in groups, the larger the pen the better, but smaller pen size may be compensated by enrichment. The developed distribution method seems efficient for determining the minimal space requirements of group-housed animals but ought to be validated further. Possible validation methods will be discussed.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.

© 2005 Noldus Information Technology bv