Effects of diet for early-weaned crossbred beef steers on metabolic profiles and febrile response to an infectious bovine herpesvirus-1 challenge

摘要

Thirty-three early-weaned steers (average age at weaning=132 days) were used to evaluate effects of protein supplementation of forage diets vs., a 70% concentrate diet fed during a backgrounding phase (84 d) on metabolic profiles and febrile responseto an infectious bovine herpesvirus-1 (BHV-1) challenge during a receiving phase (27 d) Backgrounding treatments included a bermudagrass hay diet (CTRL); CTRL plus soybean meal (SBM) fed at 0 175% of BW (as-fed); CTRL plus SBM at 0,35% of BW; or a 70% concentrate (CONG) diet. During the receiving phase, all steers were fed CONC and intranasally challenged on d 85 with an infectious dose of BHV-1 Unexpectedly, 3 d after the BHV-1 challenge, serum IgG was greater (P<0 05) for steers fed forage diets vs, CONC, Three and 4 d after the BHV-1 challenge, rectal temperatures were greater (P<0.01) for protein-supplemented steers vs, CTRL. We conclude that a higher quality diet fed to early-weaned steers during a backgrounding phase enhances average daily gain and gain to feed ratio, and increases febrile response (measured by rectal temperature) to an infectious BHV-1 respiratory challenge.