312 Effects of castration stress on behaviors and leukocyte cytokine gene expression in Korean cattle bull calves

Abstract This study investigated behavioral, physiological, and inflammatory responses, as well as leukocyte cytokine gene expression, of Korean cattle calves following surgical castration. Nineteen Korean cattle bull calves (average body weight, 254.5 kg; average age, 8.2 months) were assigned to one of two treatment groups: control (n = 9) and surgical castration (n = 10). Castration was performed surgically using Newberry knives and a Henderson castrating tool. Blood was collected immediately before castration and at 0.5 h, 6 h, 1 d, 3 d, 7 d, and 14 d after castration, and analyzed cortisol and substance P concentrations and leukocyte cytokine gene expression by quantitative real-time PCR. Behaviors were observed for 3 h, from 0.5 to 3.5 h after castration. Feed intake was recorded daily, and body weight was measured 1 d prior to the experiment and 14 d after castration. Castration decreased average daily gain (P = 0.005) and gain-to-feed ratio (P = 0.003). Castration reduced the time spent eating (P < 0.001) and the frequency of eating (P = 0.003) and increased (P < 0.001) the frequency of lying during the 3 h after castration. Castration temporarily increased circulating plasma cortisol (P < 0.001) and salivary cortisol concentrations (P = 0.03) at 0.5 h after castration. Castration temporarily increased (P < 0.05) plasma substance P concentration at 1 d after castration. Castration increased plasma haptoglobin concentration at 1 d and 3 d after castration. With regard to leukocytes, castration increased (P < 0.05) mRNA levels of inflammatory cytokine interleukin-1-beta and interleukin-1 receptor antagonist (IL1RA) genes at 6 h after castration, and increased (P < 0.05) IL1RA, interleukin-1-alpha, and interleukin-6 mRNA levels at 1 d after castration. In conclusion, castration of Korean cattle bull calves temporarily induced stress, retarded growth, and affected behaviors and inflammatory cytokine gene expression.