Effect of castration on leukocyte cytokine expression and indicators of stress and inflammation in Korean cattle bull calves

Abstract

This study investigated behavioral, physiological, and inflammatory responses, as well as leukocyte cytokine gene expression, of Korean cattle bull 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, substance P, and haptoglobin 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 < 0.05) and gain-to-feed ratio (P < 0.05). Castration reduced the time spent eating (P < 0.001) and the frequency of eating (P < 0.05) 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. Plasma cortisol and salivary cortisol was positively correlated (r = 0.69, P <0.001). 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 interleukin-1-alpha (IL-1A), interleukin-1-beta (IL-1B), interleukin-1 receptor antagonist (IL-1RN), and interleukin-6 (IL-6) at 6 h after castration, and increased (p < 0.05) IL1RN, IL-1A, and IL-6 mRNA levels at 1 d after castration. mRNA level of IL-1A and IL-1B showed a positive correlation with IL-6 (r=0.96, P < 0.001; r = 0.55, P < 0.001). mRNA level of IL-1RN was highly related to the leukocyte mRNA levels of IL-6 and IL-1B (r=0.67, P < 0.001; r=0.83. P < 0.001). In conclusion, castration of Korean cattle bull calves temporarily induced stress, retarded growth, and affected behaviors and inflammatory cytokine gene expression.