Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2012
Publication Date: 1/23/2013
Citation: Richeson, J.T., Kegley, E.B., Powell, J.G., Schaut, R.G., Sacco, R.E., Ridpath, J.F. 2013. Weaning management of newly received beef calves with or without continuous exposure to a persistently infected bovine viral diarrhea virus pen mate: Effects on rectal temperature and serum proinflammatory cytokine and haptog. Journal of Animal Science. 91(3):1400-1408 DOI:10.2527/jas.2011-4875. Interpretive Summary: Calves born persistently infected (PI) with bovine viral diarrhea virus (BVDV) may be a key source of transmission of the virus. Exposure of pen-mate calves to PI calves may suppress their immune system, leaving them susceptible to other infections. It is hypothesized that the extent of immune alteration differs for low-risk, preconditioned (PC) vs. high-risk, auction market (AM) beef calves. Our objective was to compare immune responses of PC or AM calves in presence (PI) or absence (CON) of a PI-BVDV pen-mate. Results from our study indicate potential health or growth consequences in calves exposed to a PI-BVDV pen-mate are impacted by previous management and health history.
Technical Abstract: Exposure to animals persistently infected (PI) with bovine viral diarrhea virus (BVDV) results in immunomodulation in cohorts. It is hypothesized that the extent of modulation differs for low-risk, preconditioned (PC) vs. high-risk, auction market (AM) beef cattle. Our objective was to compare immune responses of PC or AM calves in presence (PI) or absence (CON) of a PI-BVDV pen mate. Crossbred PC steers (n = 27) from a single ranch-origin were weaned, dewormed, vaccinated against respiratory and clostridial pathogens, tested for PI-BVDV, and kept on the ranch for 61 d. Subsequently, PC steers were transported to a receiving unit (RU), weighed, stratified by d-1 BW, and assigned randomly to treatment (PCPI or PCCON) with no additional processing. Simultaneously, crossbred AM calves (n = 27) were assembled from regional auction markets and delivered to the RU. The AM calves were weighed, stratified by gender and d-1 BW, processed under the same regimen used for PC steers at their origin ranch except bull calves were castrated, then assigned randomly to treatment (AMPI or AMCON). Treatment pens were arranged spatially so that PI did not have fence-line contact with CON. Blood samples were collected on d 0, 1, 3, 7, and 14 to determine serum concentrations of haptoglobin (Hp), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-4, and IL-6. Rectal temperature (RT) was recorded concurrent with blood sampling. In AM calves, RT and Hp increased (management effect; P < 0.001) sharply on d 1; however, exposure to a PI-BVDV pen-mate did not affect either parameter (P greater than or equal to 0.79) during the 14-d evaluation period. Serum concentrations of TNF-alpha tended to increase (P = 0.09) for PI cohort. A treatment × day interaction (P less than or equal to 0.05) was observed for IFN-gamma on d 7 and 14, and IL-6 on d 14; these indices were greatest for AMPI. Results indicate weaning management and PI-BVDV exposure alter the immune status of newly received beef cattle. These main effects may be additive because proinflammatory cytokine concentrations were greatest for AMPI. Therefore, results further indicate that potential health or growth consequences in cohorts exposed to a PI-BVDV pen-mate are impacted by previous management and health history.