Influences of human contact following milk-feeding on nonnutritive oral behavior and rest of individual and pair-housed dairy calves during weaning

Dairy calves are active around the time of milk-feeding and often perform nonnutritive oral behaviors, particularly during weaning. This study evaluated the interactive effects of social housing and human contact following feeding, including scratching to mimic brushing, on postfeeding nonnutritive oral behaviors and rest, during the beginning of the weaning period. We enrolled individually housed dairy heifer calves (n = 14) and pair-housed heifer calves (n = 14; 1 focal calf/pair). Human contact was provided in the form of scratching calves beneath the neck to mimic allogrooming. The human was present for 5 min, within the 15-min window following morning milk-feeding. Human contact and control days, where there was no change in the postfeeding routine, were randomized for each calf over the course of 4 consecutive days during weaning. Behavior was recorded continuously from video for 1 h following milk-feeding. Individually housed calves performed more pen-directed nonnutritive oral behavior than pair-housed calves, but provision of human contact reduced the duration of this behavior to a level that did not differ from pair-housed calves. Although human contact did not affect the duration of pen-directed nonnutritive oral behavior in pair-housed calves, cross-sucking was reduced in pair-housed calves when they received human contact. Human contact following milk-feeding reduced the total duration of all nonnutritive oral behavior (pen-directed, bedding-directed, cross-sucking, and human-directed) and increased rest with no effect of housing treatment or interaction between housing treatment and human contact. These results suggest that human contact influenced performance of nonnutritive oral behavior following milk-feeding, particularly reducing pen-directed sucking in individually housed calves, highlighting the role of restrictive environments in the expression of these behaviors in conventionally housed dairy calves.