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, peripheral blood leukocytes and serum proinflammatory cytokine and haptoglobin concentrations

Bovine respiratory disease (BRD) is a multifaceted syndrome involving physiological stress, commingling, and several viral and bacterial pathogens. Physiological alterations in response to individual stressors such as weaning, transportation, castration and commingling have been observed; however, high-risk, newly received stocker cattle are often subjected to these stressors concurrently. Whereas, the negative effects of these stressors are mitigated in cattle preconditioned on their origin ranch before marketing occurs. Bovine viral diarrhea virus (BVDV) is a major culprit in the development of BRD either directly via acute clinical disease or through indirect effects of immunosuppression. Furthermore, calves born persistently infected (PI) with BVDV are a key source of BVDV transmission and a single PI-BVDV animal has the potential to continuously expose an entire pen and adjoining pens to the virus. We hypothesized that the pro-inflammatory cytokine response would be altered by PI-BVDV exposure; however, the magnitude of physiological alteration would be impacted by previous management. The objective of our study was to determine serum pro-inflammatory cytokine and haptoglobin concentrations, total and differential blood leukocyte concentration, and rectal temperature in commingled auction market vs. single-source preconditioned calves with or without 14-d continuous exposure to PI-BVDV challenge. Materials and Methods