Objective—To determine the seroprevalence for
Neospora caninum in a population of beef calves in a
feedlot and the association of serologic status with
postweaning weight gain and carcass measurements.
Design—Longitudinal observational study.
Animals—1,009 weaned beef steers from 92 herds.
Procedure—Samples were obtained from all steers
at time of arrival at a feedlot. Serologic status for
Neospora spp was determined, using an agglutination
test. Results of serologic testing were compared with
calf growth and carcass data, using multivariate
regression with generalized estimating equations.
Results—Of 1,009 calves, 131 (12.98%) were
seropositive, and 54 of 92 (58.7%) consignments had
≥ 1 seropositive calf. Median within-consignment
prevalence for consignments in which there was ≥ 1
seropositive calf was 20%. Seropositive status was
associated with significant reductions in average daily
gain, live body weight at slaughter, and hot carcass
weight and an increase in ribeye area-to-hot carcass
weight ratio. Seropositive status also was associated
with significant increases in cost of treatment and significant
reductions in income. Sick seropositive calves
had the highest cost of treatment. An economic loss
of $15.62/calf was projected for seropositive calves.
Conclusions and Clinical Relevance—Significant
reductions in postweaning weight gain, carcass
weight, and economic return were associated with
detection of antibodies to N caninum in beef calves
in a feedlot. (J Am Vet Med Assoc 2000;217:
Objective—To determine the association between
respiratory tract infection with bovine coronavirus
(BCV), treatment for respiratory tract disease, pulmonary
lesions at slaughter, and average daily gain in
cattle in feedlots.
Animals—837 calves in feedlots in Ohio and Texas.
Procedure—Nasal swab specimens were obtained
from cattle at arrival in a feedlot (day 0) and at various
times during the initial 28 days after arrival.
Specimens were tested for BCV, using an antigencapture
ELISA. Serum samples were obtained at
arrival and again 28 days after arrival and tested for
antibodies to BCV, using an antibody-detection ELISA.
Information was collected regarding treatment for
cattle with respiratory tract disease and average daily
gain during the feeding period. Pulmonary lesions
were evaluated at slaughter.
Results—Cattle shedding BCV from the nasal cavity
and developing an antibody response against BCV
were 1.6 times more likely to require treatment for
respiratory tract disease than cattle that did not shed
the virus or develop an immune response against
BCV. Additionally, cattle that shed BCV from the nasal
cavity were 2.2 times more likely to have pulmonary
lesions at slaughter than cattle that did not shed the
virus. The BCV shedding or seroconversion status did
not affect average daily gain.
Conclusions and Clinical Relevance—Bovine coronavirus
infects feedlot cattle and is associated with an
increased risk for cattle developing respiratory tract
disease and pulmonary lesions. Development of
appropriate control measures could help reduce the
incidence of respiratory tract disease. (Am J Vet Res