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 -l (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 calv es were fitted with jugular catheters, and blood samples were collecte d every 4 h into tubes containing EDTA. Twenty-four hours later, all c alves were inoculated intranasally with BHV-1 (1 x 10(7) plaque-formin g units in each naris). Serial blood collection continued at 4-h inter vals for 6 d. Plasma was harvested, immediately frozen in liquid nitro gen, and stored at -20 degrees C. Individual rectal temperatures and u rine samples were collected at the same time each day. Rectal temperat ures 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 circad ian variation in ACTH and cortisol occurred. No differences were detec ted in the concentrations of trace minerals excreted daily in the urin e, lymphocyte proliferative response to mitogen stimulation, and neutr ophil bactericidal function. The acute phase proteins, ceruloplasmin a nd fibrinogen, also were not affected by treatment or viral challenge. These data suggest that Cr supplementation using high-Cr yeast (3 mg/ d) did not alter stress responses of calves experimentally inoculated with BHV-1.