Objective—To determine association between exposure to Neospora caninum and milk production in dairy cows.
Design—Prospective observational study.
Animals—565 Holstein cows.
Procedure—Cows were classified as seropositive or seronegative to N caninum within 7 days after calving by use of a kinetic ELISA. Milk production was compared between seropositive and seronegative cows.
Results—On the basis of 305-day mature equivalent milk production data, seropositive cows produced less milk (2.8 lb/cow per day) than did seronegative cows. In addition, analysis of results throughout the first 300 days of lactation revealed that after adjusting for effects of lactation number, calving season, clinical mastitis, and lameness, milk weight of seropositive cows was 2.5 lb/cow per day less than that of seronegative cows.
Conclusions and Clinical Relevance—Exposure to N caninum was associated with a 3 to 4% decrease in milk production. A decrease in milk production of 800 lb/cow for a typical 305-day lactation represents a loss of $128/cow. (J Am Vet Med Assoc 2001; 219:632–635)