Communal rearing of rabbits affects space use and behaviour upon regrouping as adults

To study the effect of early social experience on the behaviour of adult female breeding rabbits, two rearing strategies were used. Litter-reared (LITREAR) rabbits were reared with littermates and their mother only. Communally reared (COMREAR) rabbits were also reared with littermates and their mother, but from 18 days of age on they were grouped with 3 other litters and their mothers. As adults (from 3 days before their 1st parturition on) both COMREAR and LITREAR rabbits were housed in pens consisting of 4 individual units, each furnished with an elevated platform. Eighteen days post-partum the 4 units per pen were merged by removing the dividers between the units, thus creating group pens each housing 4 unfamiliar adult rabbits and their litters. Four COMREAR and 4 LITREAR groups were video recorded during the 1st 48h after grouping, and 192 scan-samples were made per group. Fewer COMREAR than LITREAR rabbits were found within 25 cm of an adult conspecific du ring the 1st 24h (32 vs. 41% ± 2 SEM), but this difference disappeared during the 2nd 24h (39 vs. 40% ± 2 SEM, rearing*time interaction: F1,264.1=4, P=0.06). The percentage of rabbits in physical contact with a conspecific was not significantly affected by rearing or time (P>0.10, mean: 12% ± 23 STD), but COMREAR rabbits spent less time in the part of the pen to which they had been confined around parturition than LITREAR rabbits (30 vs. 39 % ± 1 SEM, F1,296.7=26, P<0.0001). Use of the elevated platform did not differ significantly between the rearing strategies (P>0.10), but was higher in the 2nd than in the 1st 24h (26 vs. 17 % ± 3 SEM, F1,111.5=8, P<0.01). Agonistic behaviour and social sniffing were not affected by the rearing strategy (P>0.10), but were observed more often in the 1st than in the 2nd 24h (agonistic: 1.7 vs. 0.6% ± 0.3 SEM, F1,511.9=8 , P<0.01, sniffing: 1.3 vs. 0.7% ± 0.2 SEM, F1,477.7=4, P=0.05). COMREAR rabbits spent less time eating/drinking than LITREAR rabbits (9 vs. 12% ± 1 SEM, F1,469.8=7, P<0.01), tended to spend less time interacting with kits (0.9 vs. 1.3% ± 0.2 SEM, F1,469.7=3, P=0.095), and spent more time sitting/lying (73 vs. 68% ± 1 SEM, F1,442.4=13, P<0.01). During the first 24h only, COMREAR rabbits spent less time on cage manipulation than LITREAR rabbits (1.3 vs. 3.1% ± 0.4 SEM, F1,473.5=4, P=0.04). In summary, communal rearing affected behaviour upon regrouping as adults, decreasing the time spent in proximity of adult conspecifics, attraction to the former home unit and activity, without significantly affecting social and contact behaviour. Whether communal rearing can aid in reducing unwanted social behaviour in group housed breeding rabbits requires further study.