Evaluation of endocrine and immune responses of steers challenged with infectious bovine rhinotracheitis virus

Objective—To evaluate the endocrine and immune responses of steers challenged with infectious bovine rhinotracheitis virus (IBRV). Animals—12 crossbred beef steers. Procedures—Steers were randomly assigned to IBRV– (control) or IBRV+ treatment groups. Experimentally challenged steers (IBRV+) received a dose of IBRV intranasally (8.0 50% tissue culture infective doses), IBRV– steers received a saline (0.9% NaCl) solution placebo intranasally, and each group was placed in an isolated paddock. At 72 hours after challenge, all steers were fitted with indwelling jugular catheters and placed into individual stanchions. Blood samples were collected on days 4 through 8. Serum was analyzed for concentrations of cortisol, interleukin-6, interferon-γ, tumor necrosis factor-α, growth hormone, and insulin-like growth factor I. Results—From 72 to 144 hours after challenge inoculation, the IBRV+ group had significantly greater mean rectal temperature, compared with the IBRV– group; the greatest temperatures in both grou...