Effect of Male Rabbit Urine on Aggressiveness and Affiliative Interactions in Group-Housing of Unfamiliar Mature Females

Rabbits are one of the most commonly used animals in biomedical research. Despite being social animals they are usually kept individually in cages in the research facilities. One limitation to the group-housing is aggression when mixing strange adult animals. Some studies have shown that male urine is effective in decrease the aggressiveness between female animals. We evaluated the behaviour of two groups of 4 unfamiliar adult female New Zealand White rabbits during 4 days. One group of animals was sprayed with buck urine prior to the formation of the group, the other group serves as control. The animals were tested in a large pen with an enriched environment in order to facilitate social housing. There were no main effects of treatment on the studied behaviours (aggression, social and agonistic behaviour, allogrooming and mounting). In both groups, the frequency of attacks was highest the first day and thereafter decrease considerably by day 4. Regarding social and agonistic behaviours, both increased progressively from day 1 to day 3, and decreased from day 3 to day 4. The food intake and body weight during the study was similar between control and treatment groups. No remarkable lesions were found. The findings indicate that urine had little or no effect at reducing aggression between the animals. Nevertheless, the adaptation of the animals to the groups was easily achieved within a few days. We propose that providing a large space and enriched environment will facilitate the socialization of unknown female adult rabbits.