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Hyperketonemia is a common disease in early lactating dairy cows and diagnosed by measurement of blood β-
hydroxybutyric acid. The objectives of our study were to describe the occurrence of hyperketonemia within the first
six weeks of lactation and to evaluate the effects of hyperketonemia on milk production (1st test day milk yield and
100 DIM milk yield), reproductive performance (time to first service, first service conception risk, and time to
pregnancy within 200 DIM) and early lactation culling risk.
A total of 655 Holstein dairy cows from 6 commercial dairy farms in Germany were enrolled between 1 and 4
DIM. Cows were tested twice weekly using an electronic handheld meter for β-hydroxybutyric acid for an
examination period of 42 days resulting in 12 test results per cow. Hyperketonemia was defined as a β-
hydroxybutyric acid concentration ≥ 1.2 mmol/l. The onset of hyperketonemia was described as early onset (first
hyperketonemia event within the first 2 weeks postpartum) and late onset (first hyperketonemia event in week 3 to 6
postpartum). Prevalence and incidence of hyperketonemia were assessed based on the 12 examinations.
Cumulative incidence of hyperketonemia was 48% and 72% for primiparous and multiparous cows, respectively.
Mean prevalence was 17.5%. Early onset ketotic cows had a higher 1st test day milk yield (+3.0 kg/d, P<0.001) and
100 DIM milk production (+301.6 kg; P<0.001) compared to non-ketotic cows. There was no effect of late onset of
ketosis on milk production. There were no effects of hyperketonemia on reproductive performance and culling risk,
irrespective of onset of ketosis.