title: Neospora caninum serostatus and milk production of Holstein cattle.
abstract: 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.
authors.affiliation: Department of Population Medicine, Ontario Veterinary College, Guelph, Canada.
authors.forename: Jamie C
authors.initials: JC
authors.lastname: Hobson
authors.forename: Todd F
authors.initials: TF
authors.lastname: Duffield
authors.forename: David
authors.initials: D
authors.lastname: Kelton
authors.forename: Kerry
authors.initials: K
authors.lastname: Lissemore
authors.forename: Sharon K
authors.initials: SK
authors.lastname: Hietala
authors.forename: Ken E
authors.initials: KE
authors.lastname: Leslie
authors.forename: Beverly
authors.initials: B
authors.lastname: McEwen
authors.forename: Gerard
authors.initials: G
authors.lastname: Cramer
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Peregrine
mesh_terms: 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
chemical_list: D000913:Antibodies, Protozoan