Oral and Poster Abstracts

109 Association between Johne’s Disease Milk ELISA Test Result
and Milk Production and Breed in Canadian Dairy Cows
U. Sorge 1 , D. Kelton 1 , W. Sears 1 , J. Jansen 2 , A. Godkin 2 , R. Cantin 3
1
University of Guelph, Department of Population Medicine, Guelph,
Canada
2
OMAFRA, Department of Population Medicine, Fergus, Canada
3
CanWest DHI, Guelph, Canada
Johne’s Disease is often described as a production limiting disease. The
objective of this study was to quantify the difference in milk production
of JD milk ELISA positive cows and test negative cows, as well as to
evaluate variations in test results due to breed. The test day information
from 4,390 cows from 80 CanWest DHI herds in Ontario was available
for this analysis. The cows were tested between March 2005 and March
2006 with the AntelBio Johne’s Milk ELISA. A mixed model was
fitted to investigate the association of a positive milk ELISA test with
the estimated cumulative 305 day milk production. Only factors with a
p-value 12 months of age) seropositive
(ELISA) for MAP in a national whole herd serosurvey. Control herds
were matched to case herds on the basis of the year of diagnosis of
PTB in the case herds. Statistical analyses were performed using uniand
multivariate conditional logistic regression with the herd as the
experimental unit. Factors relating to disease history, herd size,
neonatal feeding and management and grassland management were
found to be significantly associated with herd PTB status (P