|Briggs, Robert - Bob|
Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2006
Publication Date: 8/1/2006
Citation: Thomas, C.J., Hoet, A.E., Sreevatsan, S., Wittum, T.E., Briggs, R.E., Duff, G.C., Saif, L.J. 2006. Transmission of bovine coronavirus and serologic responses in feedlot calves under field conditions. American Journal of Veterinary Research. 67(8):1412-1420. Interpretive Summary: Calves (203) were studied, from before shipping through 35 days after arrival at a feedlot, for infection by and serological response to bovine coronavirus. Calves from a single ranch (103) had high serum antibodies to coronavirus prior to shipment and few were infected in the feedlot. Calves procured by an order-buyer from multiple sources (100) had much lower antibody titers prior to shipment and approximately 2/3 of these calves became infected in their nasal passages and gastrointestinal tract. Bovine coronavirus infection was significantly associated with respiratory tract disease and decreased growth performance in the latter group of calves. Circumstantial evidence indicates that the bovine coronavirus may start in the upper respiratory tract and spread to the gastrointestinal tract. Vaccination against bovine coronavirus may be beneficial to reduce respiratory disease losses in at least some groups of feedlot calves.
Technical Abstract: To compare shedding patterns and serologic responses to bovine coronavirus (BCV) in feedlot calves shipped from a single ranch in New Mexico (NM calves) versus calves assembled from local sale barns in Arkansas (AR calves) and to evaluate the role of BCV on disease and performance. Animals: 103 feedlot calves from New Mexico and 100 from Arkansas. Calves were studied from before shipping to 35 days after arrival at the feedlot. Nasal swab specimens, fecal samples, and serum samples were obtained before shipping to 35 days after arrival, and periodically thereafter. Bovine coronavirus antigen and antibodies were detected by use of an ELISA. NM calves had a high geometric mean titer for BCV antibody at arrival (GMT, 1,928); only 2% shed BCV in nasal secretions and 1% in feces. In contrast, AR calves had low antibody titers against BCV at arrival (GMT, 102) and 64% shed BCV in nasal secretions and 65% in feces. Detection of BCV in nasal secretions preceded detection in feces before shipping AR calves, but at arrival, 73% or AR calves were shedding BCV in nasal secretions and feces. Bovine coronavirus infection was significantly associated with respiratory tract disease and decreased growth performance in AR calves. Replication and shedding of BCV may start in the upper respiratory tract and spread to the gastrointestinal tract. Vaccination of calves against BCV before shipping to feedlots may provide protection against BCV infection and its effects with other pathogens in the induction of respiratory tract disease.