Effect of health status on culling and reproductive performance of Holstein cows.

Data were from 492 cows that calved between October 1976 and May 1977 in eight Holstein herds in Michigan. Cows were classified as those without any health-related problems during lactation; those with minor reproductive health problems not serious enough to require veterinary treatment; and those with health problems severe enough to require veterinary treatment. Among primiparous cows 4.4, 16.2, and 19.1% were culled from healthy, minor, and problem groups, whereas among multiparous cows, these percentages were 11.2, 19.1, and 31.7. Among healthy cows 33.3, 38.9, and 27.8% of total culls were classified as production, reproduction, and other. Among minor and problem cows, these percentages were 31.6, 42.1, and 26.3 and 22.6, 58.5, and 18.9. The odds of being culled were 4.3 and 5.2 times as great as for first lactation cows in minor and problem groups and 1.9 and 3.7 times as great as for older cows in the two health-problem groups. Primiparous cows in healthy group averaged 50 days to first detected estrus, 68 days to first service, and 95 days open. Least squares means for performance of primiparous cows in minor and problem groups and of multiparous cows in healthy, minor, and problem groups, as deviations from healthy cows, was days to first service, 9.1, 24.0, 2.0, 12.1, and 9.1; and days open, -7.0, 15.2, -9.1, 1.8, and 12.6. Primiparous cows with health problems were at a higher risk of being culled than multiparous cows with health problems.