Transmission of bovine coronavirus and serologic responses in feedlot calves under field conditions.
OBJECTIVE
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.


METHODS
103 feedlot calves from New Mexico and 100 from Arkansas.


METHODS
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, at arrival, and periodically thereafter. Bovine coronavirus antigen and antibodies were detected by use of an ELISA.


RESULTS
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% of 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.


CONCLUSIONS
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.
Thomas
Christopher J
CJ
Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, 44691, USA.
Hoet
Armando E
AE
Sreevatsan
Srinand
S
Wittum
Thomas E
TE
Briggs
Robert E
RE
Duff
Glenn C
GC
Saif
Linda J
LJ
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001826:Body Fluids / Q000821:virology; D002417:Cattle; D002418:Cattle Diseases / Q000635:transmission* / Q000821:virology; D018352:Coronavirus Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D017938:Coronavirus, Bovine; D005243:Feces / Q000821:virology; D012140:Respiratory Tract Diseases / Q000662:veterinary* / Q000821:virology; D017201:Virus Shedding
D000914:Antibodies, Viral