Effects of weaning programs on metabolic profiles and hepatic IGF-1 mRNA of first-calf heifers and mature cows, and effects of diet for early-weaned steers on response to an infectious bovine herpesvirus-1 challenge
AuthorWhitney, Travis Raymond
AdvisorDuff, Glenn C.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractEffects of weaning on metabolic profiles and hepatic IGF-1 mRNA of beef dams (Trial 1), and diet effects for early-weaned (EW) steers on response to an infectious bovine herpesvirus-1 (BHV-1) challenge (Trial 2) were investigated. Trial 1 treatments were arranged in a 2 x 2 factorial and included 14 heifers and 14 cows assigned randomly to one of two treatment regimens: EW (average age of 114 ± 13 d) or normal-weaned (NW, average age of 197 d). Heifers with calves EW experienced a greater increase (parity x weaning; P = 0.02) in BW over heifers with calves NW, but no change in BW due to weaning was observed for cows (P > 0.71). Early weaning (vs. NW) increased (P < 0.05) body condition (BC) and change in BC of all dams. No parity x weaning or parity x weaning x d interactions (P > 0.14) were observed for serum IGF-1, NEFA, or urea nitrogen (SUN). A parity x d interaction (P < 0.05) for hepatic IGF-1 mRNA, serum IGF-1, and SUN was observed, but no differences (P > 0.10) were detected between heifers and cows within d. For Trial 2, backgrounding treatments included a bermudagrass hay diet (CTRL); bermudagrass hay plus soybean meal (SBM) fed at 0.175% of BW (as-fed); bermudagrass hay plus SBM at 0.35% of BW; or a 70% concentrate (CONC) diet. During the receiving phase, all steers were fed CONC and intranasally challenged with BHV-1. Treatment x d interactions (P < 0.01) were observed for serum NEFA, total protein, SUN, glucose, immunoglobulin G (IgG), insulin, and rectal temperature. Three d after the BHV-1 challenge, IgG was greater (P < 0.05) for forage-fed steers vs. CONC. Three and 4 d after the challenge, rectal temperature was greater (P < 0.01) for protein supplemented steers vs. CTRL. Therefore, EW can increase BW and BC of first-calf heifers and decrease SUN in first-calf heifers and mature cows, and a higher quality diet fed to EW steers during a backgrounding phase enhances ADG and G:F, and increases febrile response (measured by rectal temperature) to an infectious BHV-1 respiratory challenge.
Degree ProgramGraduate College