Supplemental dietary chromium does not influence ACTH, cortisol, or immune responses in young calves inoculated with bovine herpesvirus-1.

Twelve Holstein bull calves (6 to 8 wk of age) were used to determine the influence of supplemental dietary Cr on ACTH, cortisol, and immune responses of calves experimentally inoculated with bovine herpesvirus-1 (BHV-1). Calves supplemented with Cr received 3 mg Cr/d (Chromium, n = 6) of a high-Cr-yeast product. Following 53 d of treatment, all calves were fitted with jugular catheters, and blood samples were collected every 4 h into tubes containing ETDA. Twenty-four hours later, all calves were inoculated intranasally with BHV-1 (1 x 10(7) plaque-forming units in each naris). Serial blood collection continued at 4-h intervals for 6 d. Plasma was harvested, immediately frozen in liquid nitrogen, and stored at -20 degrees C. Individual rectal temperatures and urine samples were collected at the same time each day. Rectal temperatures were elevated (P < .05) on d 2, 3, 4, and 5 but were not affected by Cr treatment. Treatment with Cr did not affect secretion of ACTH, cortisol, or plasma tumor necrosis factor-alpha, although clear circadian variation in ACTH and cortisol occurred. No differences were detected in the concentrations of trace minerals excreted daily in the urine, lymphocyte proliferative response to mitogen stimulation, and neutrophil bactericidal function. The acute phase proteins, ceruloplasmin and fibrinogen, also were not affected by treatment or viral challenge. These data suggest the Cr supplementation using high-Cr yeast (3 mg/d) did not alter stress responses of calves experimentally inoculated with BHV-1.