Neospora caninum serostatus and milk production of Holstein cattle.
OBJECTIVE
To determine whether Neospora caninum serostatus was associated with milk production among Holstein cattle in Ontario.


METHODS
Case-control study and cross-sectional observational study.


METHODS
3,702 Holstein cows in 83 herds (case-control study) and 3,162 Holstein cows in 57 herds.


METHODS
Herds in the case-control study were grouped on the basis of N. caninum abortion status. Herds in the observational study were considered representative of Ontario dairy herds. The N. caninum serostatus of individual cows was determined with a kinetic ELISA. Milk production was modeled to compare seropositive with seronegative animals while controlling for parity, days since parturition, and herd clustering.


RESULTS
In the case-control study, 305-day milk production of seropositive cows was significantly less than milk production of seronegative cows in herds with abortions attributable to N. caninum infection and in herds with abortions attributable to pathogens other than N. caninum, but not in herds without abortion problems. In the observational study, 305-day milk production for seropositive cows was not significantly different from milk production of seronegative cows.


CONCLUSIONS
Results suggest that the association between N. caninum serostatus and milk production in Ontario Holstein dairy cattle may depend on abortion status of the herd. In herds with abortion problems, regardless of cause, N. caninum-seropositive cattle produced less milk, whereas in herds without abortion problems, N. caninum-seropositive cattle produced the same amount of milk as seronegative cattle.
Hobson
Jamie C
JC
Department of Population Medicine, Ontario Veterinary College, Guelph, Canada.
Duffield
Todd F
TF
Kelton
David
D
Lissemore
Kerry
K
Hietala
Sharon K
SK
Leslie
Ken E
KE
McEwen
Beverly
B
Cramer
Gerard
G
Peregrine
Andrew S
AS
D000034:Abortion, Veterinary / Q000453:epidemiology / Q000469:parasitology; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D016022:Case-Control Studies; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000469:parasitology / Q000503:physiopathology*; D003048:Coccidiosis / Q000453:epidemiology / Q000503:physiopathology / Q000662:veterinary*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D007774:Lactation; D007775:Lactation Disorders / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary; D008892:Milk / Q000378:metabolism*; D018688:Neospora / Q000276:immunology*; D009864:Ontario / Q000453:epidemiology; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000453:epidemiology / Q000662:veterinary; D011446:Prospective Studies; D016036:Seroepidemiologic Studies
D000913:Antibodies, Protozoan