Zomeño, C., Birolo, M., Zuffellato, A. et al. 2017. Aggressiveness in group-housed rabbit does: Influence of group size and pen characteristics. Applied Animal Behaviour Science 194, 79-85.
The aim of this work was to study how the group size and the number of doorways in a pen may influence the aggressive interactions throughout the reproductive cycle among does kept in a part-time group housing system. Thirty-two crossbred multiparous pregnant rabbit does were housed in individual modules (0.5m2) that were connected to form collective pens with two (P2) or four (P4) does (8 and 4 replications, respectively) by using one (D1) or two (D2) doorways. The females were maintained in stable groups from the start of the trial, 8 d before kindling (−8 d), until 2 d before kindling and from 18 d after kindling (+18 d) until weaning (31 d). The aggressive interactions were video recorded through 24 consecutive hours at −8 d and +18 d and at 21 d and 30 d after kindling. Aggressive behaviour at 21 d and 30 d after kindling was not analysed due to its scarce (total interactions per doe in 24h: 0.02 events) and null occurrences, respectively. Then, data of the first hour after grouping at −8 d and +18 d were analysed by Bayesian inference, and the posterior distributions of the differences between group size, number of doorways and observation day were estimated. Does in P4 pens showed a higher frequency of boxing (1.63 vs. 0.50 events per doe) and chasing (1.00 vs. 0.28) than those in P2 pens (probability of relevance, ProbR=0.87). Does in D2 pens showed a higher frequency of attacking (2.00 vs. 0.46 events per doe), chasing (0.83 vs. 0.21), and mount attempts (0.38 vs. 0.08) than those in D1 pens (ProbR 0.80–0.83). Aggressive interactions were higher at the first group formation (−8 d) than at regrouping (at +18 d) (10.5 vs. 6.25 events per doe; ProbR=0.69). In conclusion, aggression among does was affected by group size and pen characteristics and decreased throughout the reproductive cycle. Nevertheless, studies of more reproductive cycles and collective pens will be necessary to confirm the present results.