Milk production in Swedish primiparous dairy cows associated with calfhood rearing and health.

SUMMARY Associations of first-lactation milk production with calfhood rearing conditions and health were studied in 2,060 dairy heifers in 107 Swedish herds. Milk production at first test-day after calving (median 27.1 range 7.9–48.0 kg) and during first 305 days of lactation (median 8006; range 3,764–12,136 kg) were modelled. High age at calving was associated with higher production, indicating that high prepubertal weight gain can be compatible with high milk production. Calfhood diarrhoea and fatness at 1 st service was associated with a low production. The results indicate that accustoming heifers to large amounts of concentrates before calving is beneficial.