Lifetime performance traits of Holstein cows: implications of first-lactation milk yield and culling causes.

The study examined the impacts of first-lactation milk yield and culling causes on lifetime performance traits in Holstein cows culled after their second to sixth parities. Complete lactations from 12,209 records belonging to 4522 culled cows were included in the study. Reproductive problems, mastitis, metabolic disorders, lameness, endemic diseases, and respiratory diseases represented culling causes. The resulting means were 371 ± 2.0 days for days in milk 30,223 ± 374 kg for lifetime milk yield, 13.5 ± 0.4 kg for milk per day of cow age, 38 ± 0.4 months for productive life, 68 ± 0.4 months for longevity, 3.6 ± 0.05 for services per conception, and 437 ± 3.4 days for calving interval. The first-lactation milk yield was associated with lifetime milk yield, milk/day of age, no-services/conceptions, and calving intervals. Cows culled for reproductive problems exhibited the greatest longevity, whereas those culled for endemic diseases had the shortest. Cows culled for lameness achieved the highest lifetime milk yield, while cows culled for metabolic disorders showed the highest milk yield per day of cow age. Furthermore, reproductive problems, metabolic diseases, or mastitis caused a higher number of no-services/conceptions and calving intervals compared with the other culling causes. In conclusion, higher first lactation milk yield was associated with higher productivity and lower reproductive performance. Moreover, the lifetime performance of culled cows differed according to the reason for culling. Dairy management programs should address reasons for culling in terms of their interrelationships, as one reason may cause or promote the appearance of another.