Neospora caninum serostatus and milk production of Holstein cattle

Jamie C. Hobson Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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 BSc, DVM
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Todd F. Duffield Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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David Kelton Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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 DVM, PhD
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Kerry Lissemore Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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Sharon K. Hietala California Animal Health and Food Safety Laboratory System, University of California, Davis, CA 95616.

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 PhD
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Ken E. Leslie Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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 DVM, MSc
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Beverly McEwen Animal Health Laboratory, University of Guelph, Guelph, ON N1G 2W1, Canada.

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Gerard Cramer Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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Andrew S. Peregrine Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.

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 BVMS, PhD, DVM

Abstract

Objective—To determine whether Neospora caninum serostatus was associated with milk production among Holstein cattle in Ontario.

Design—Case-control study and cross-sectional observational study.

Animals—3,702 Holstein cows in 83 herds (casecontrol study) and 3,162 Holstein cows in 57 herds.

Procedure—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 and Clinical Relevance—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. (J Am Vet Med Assoc 2002;221:1160–1164)

Abstract

Objective—To determine whether Neospora caninum serostatus was associated with milk production among Holstein cattle in Ontario.

Design—Case-control study and cross-sectional observational study.

Animals—3,702 Holstein cows in 83 herds (casecontrol study) and 3,162 Holstein cows in 57 herds.

Procedure—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 and Clinical Relevance—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. (J Am Vet Med Assoc 2002;221:1160–1164)

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