Effect of Neospora caninum infection on milk production in first-lactation dairy cows.
OBJECTIVE
To determine whether cows seropositive to Neospora caninum produced less milk during their first lactation than seronegative cows.


METHODS
Repeated-measures, prospective study.


METHODS
372 Holstein cows in their first lactation.


METHODS
Cows were tested repeatedly before and during their first lactation for antibodies to N caninum. One-way and repeated-measures ANOVA were used to determine whether mean daily milk weights and milk weights from Dairy Herd Improvement Association testing were less for seropositive cows than for seronegative cows.


RESULTS
Weekly mean daily milk weights for the 118 seropositive cows were significantly less than those for the 254 seronegative cows, and milk production for seropositive cows (mean, 55.2 lb/cow/d) was 2.5 lb/cow/d less than that for seronegative cows (mean, 57.7 lb/cow/d). Analysis of results from Dairy Herd Improvement Association testing revealed that production of seropositive cows was less for milk (3.1 lb/cow/d), fat-corrected milk (3.6 lb/cow/d), and fat (0.14 lb/cow/d) than production of seronegative cows.


CONCLUSIONS
The economic impact of N caninum infection in dairy cows can include reduced revenues from decreased milk production, which may warrant culling of young, seropositive replacement stock.
Thurmond
M C
MC
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA.
Hietala
S K
SK
D000704:Analysis of Variance; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D002417:Cattle; D002418:Cattle Diseases / Q000191:economics / Q000503:physiopathology*; D003048:Coccidiosis / Q000150:complications / Q000191:economics / Q000503:physiopathology / Q000662:veterinary*; D005260:Female; D005500:Follow-Up Studies; D007774:Lactation; D007775:Lactation Disorders / Q000191:economics / Q000209:etiology / Q000662:veterinary*; D008892:Milk / Q000378:metabolism; D018688:Neospora / Q000276:immunology; D011446:Prospective Studies
D000913:Antibodies, Protozoan