Culling associated with Neospora caninum infection in dairy cows.

OBJECTIVES

To estimate the extent to which cows infected with Neospora caninum were culled, compared with noninfected cows, and to identify differences in reasons for culling between infected and noninfected cows.

ANIMALS

442 Holstein cows on a commercial dairy with 36% seroprevalence for N caninum.

PROCEDURE

Culling of cows was done after first calving without knowledge of N caninum serologic status.

RESULTS

Risk of a seropositive cow dying was not different from that of a seronegative cow (P = 0.50). Seropositive cows were culled 6.3 months earlier than seronegative cows, and had a 1.6 times greater risk of being culled, compared with seronegative cows (P = 0.004), after adjusting for culling risk associated with abortion. For cows culled for low milk production, culling risk for a seropositive cow was twice that for a seronegative cow (P = 0.007).

CONCLUSIONS

The economic impact of N caninum infection in dairy cattle can be expected to extend beyond that for abortion alone. Costs of the disease also may include premature culling and diminished milk production.

CLINICAL RELEVANCE

Plans to control N caninum infection on dairies should include consideration that benefits may include reduction in premature culling and increase in milk production.