Effects of Pen Relocation at Weaning on Behavioral Changes and Stress in Japanese Black Calves.

The effects of pen relocation at dam-calf separation on behavioral changes and stress were examined in Japanese Black calves. Male and female calves were randomly assigned at 4 months of age to one of two groups: a non-relocation group, in which the dam was moved to a separate pen while the calf remained in its original pen; and a relocation group, in which the calf was moved while the dam remained in place. Calves were observed for step counts per 24 h and vocalizing counts per 12 h and per hour, and for time spent feeding, lying, and ruminating over 12-h periods around weaning. Blood samples were collected for hematological analysis and serum cortisol assay just before and after weaning. Calves in the non-relocation group had significantly fewer steps and less vocalization than those in the relocation group after weaning. Postweaning lying, feeding, and ruminating times were significantly longer in the non-relocation group than in the relocation group. Neutrophil-to-lymphocyte ratio and serum cortisol concentrations were also significantly lower in the non-relocation group after weaning. These findings suggest that avoiding pen relocation of calves during weaning may alleviate behavioral disturbances and reduce stress associated with maternal separation in Japanese Black cattle.