Changes in activity, spatial pattern and social behavior in calves after grouping

The behavior of 2 groups of 6 calves that were managed in 2 different ways were observed, and the development of their behavioral patterns, spatial patterns and social behavior in the groups were discussed, together with the effect on these processes of their social experience before grouping.

Twelve 5-month-old Holstein steers, reared alone from one week of age, were divided into 2 groups of 6 calves each; Groups A and B. Calves in Group A were penned together in a 14.4 × 28.8 m pen, and the position and behavior of individuals was observed throughout a continuous 153-h period at 15-min intervals. Aggressive behavior between calves was also recorded. The position of calves was recorded as coordinates on a grid on the pen floor. There were 8 × 16 squares in the grid, and each square measured 1.8 × 1.8 m.

Group B was further divided into 3 groups of 2 calves each, which were kept in 9.6 × 14.4 m pens. The pair-mates were changed every 3 days in order to combine all possible pairs in the group. After this treatment, calves were all housed together in a 14.4 × 28.8 m pen, and observed using the same methods and for the same duration as Group A.

The lying pattern of Group A was not diurnal until the latter half of the observation, while calves in Group B showed clear-cut diurnal variations from the initial stages. Concerning the spatial patterns; the mean distance to nearest neighbor in Group A tended to decrease and become stable. The ratio between the mean distance to nearest neighbor and the distance expected in random distribution also declined from 0.7 to a significant aggregation of 0.5 (P < 0.05). For Group B, a similar change in the mean distance to the nearest neighbor was observed, although this showed significant aggregation from the first 24-h period (P < 0.05). The mean area occupied by a group in each 24-h period, for both groups, declined for 72 h after grouping and became stable at around 18 m², for both groups, thereafter. The frequency of aggression in Group A declined from 23 times in the first 24-h period to 9 times at the end of the observation period. For Group B, the aggression frequency was 53 times in the first 24-h period, thereafter decreasing rapidly.