Weaning reactions in beef cattle are adaptively adjusted to the state of the cow and the calf.

Abrupt weaning as practiced in beef cattle husbandry is stressful for both the cow and her offspring. However, the reaction to weaning varies among individuals. Based on the theory of maternal care allocation, we derived and tested the following hypotheses: 1) cow reaction to weaning will be stronger if the calf is young, if the calf is a female, and if the calf had higher daily weight gain; 2) cows in a higher parity and cows that are not concurrently pregnant will react more on weaning; and 3) young and female calves, and also calves with higher daily weight gain will respond more to weaning. We recorded frequency of vocalization and time spent moving in 50 cow-calf pairs (27 males and 23 females) immediately after weaning at 151 to 274 d of age. The recordings were made at 0 to 2 h, 6 to 8 h, and 24 to 26 h after the separation of the calves from the cows. Linear mixed models were used to test the predictions. In cows, age of the calf had the strongest effect with mothers of younger calves vocalizing more ( < 0.05). Frequency of vocalization was higher in mothers of calves with higher daily weight gain ( < 0.01) and in nonpregnant mothers ( < 0.01). Frequency of the moving was higher in younger cows ( < 0.05). Sex of the calf had no effect. In calves, females vocalized ( < 0.001) and moved ( < 0.01) more than males and calves with higher daily weight gain also called more ( < 0.01). The relationships between the 2 behaviors and their time courses were different in cows and calves. In cows, vocalization and movement were correlated ( < 0.001) and both increased until 6 to 8 h and then plateaued or declined ( < 0.001). In calves, vocalizations steadily increased until 24 to 26 h ( < 0.001) whereas movement remained unchanged in time and was uncorrelated with vocalizations. These differences indicate that vocalization may be a more sensitive indicator of weaning stress than movement. Our results document that the ability to adaptively adjust mother-young interactions has been preserved in domesticated beef cattle.