Effects of freeze or hot-iron branding of angus calves on some physiological and behavioral indicators of stress

Abstract

Twenty-four Angus calves averaging 293 ± 38 kg were either hot-iron branded (H), freeze branded (F), or served as a sham (S). Calves were blocked for temperament, weight, and sex, and randomly assigned to day and order in which treatments were applied. To reduce stress from handling at treatment time, each calf was herded through the squeeze chute for 5 days prior to the experiment. Jugular cannulae were established in each calf 1 day prior to application of treatment. Blood samples and heart rate were obtained at −5 and −3 min prior to and 0, 0.5, 1, 3, 5, 10, 15 and 20 min after calves were branded on the hip. Mean plasma cortisol concentration increased for all treatments during the sampling times ( P = 0.0001). Mean plasma epinephrine concentration was greater ( P < 0.01) for H calves at 0.5 min after branding than either S or F calves. Hot-iron branded calves had greater ( P < 0.02) mean heart rate during branding and 30 s post-branding than did either S or F calves. The escape-avoidance reaction of H calves, quantified as the amount of vertical movement the calf exhibited during branding, was also greater ( P < 0.05) than either the F or S calves. Five H calves, four F calves, and no S calves vocalized during treatment. The greater escape-avoidance reaction as well as the elevated heart rate and plasma epinephrine concentration of the H calves indicate that a greater pain sensation is perceived by hot-iron branded Angus cattle.