Social behavior of young dairy calves housed with limited or full social contact with a peer1

This study compared the effect of individual and pair housing and age at pair housing on the social behavior of young dairy calves. Twenty-seven pairs of calves were reared from birth until 6 wk either individually (limited social contact between bars; L calves), in pairs (full social contact; F calves), or individually for 3 wk and in pairs for the next 3 wk (LF calves). From 6 to 7 wk of age, the calves were housed in a group of 6 calves (each group consisted of 3 pair of calves, 1 pair from each treatment). Video recordings of undisturbed behavior were obtained from each pair on d 2, 12, 22, and 34 (age of the youngest calf in a pair) and from the group pens on d 44 and 49 (age of the youngest calf in the group). Behavioral recordings were performed using instantaneous recording at 5-min intervals on d 2, 22, and 34 over 16 h to investigate overall activity and social activity of the pairs. Six of 6 F calves and 2 of 6 L calves were sniffing and licking another calf on d 2. Calves from treatments F and LF were sniffing and licking another calf more on d 22 compared with on d 34, but we observed no difference between treatments F and LF. On both days, the F calves and LF calves were sniffing and licking another calf more than were the L calves. No difference was found in duration of lying down in body contact with another calf between F and LF calves on d 22; however, on d 34, LF calves performed more of this behavior than did F calves. Continuous recordings of social behavior were conducted for 3 h on d 12 and 34. On d 12, we found no difference between F and L calves in the total duration of being actively engaged in social behaviors. On d 34, F and LF calves were more actively engaged in social behaviors than were the L calves. After grouping, lying behavior and nearest neighbor during rest were recorded instantaneously at 15-min intervals for 16 h on d 44 and 49. From d 44 to 49, the duration of resting increased, the duration of resting with a neighbor increased, and the duration of resting with the previous companion decreased. No difference was found between treatments after grouping in duration of rest and rest with a neighbor. In conclusion, from the age of 3 wk of life, calves housed with full social contact performed more social behaviors than calves housed individually with limited social contact, whereas only minor differences were found in the social behavior of calves housed together from birth compared with those housed together from 3 wk of life.