Relationships among β-hydroxybutyrate, calcium and non-esterified fatty acids in blood with milk yield losses at early lactation

The objectives were to study the associations of concentrations of beta-hydroxybutyrate acid (BHBA), calcium (Ca2+), and non-esterified fatty acids (NEFA) in blood serum 7 d prepartum with losses in milk yield (MY) and metabolic dysfunctions at seven and 14 d of lactation. Three hundred and thirty-six (336) Holstein-Friesian (780 +/- 36 kg BW; which had lactated more than twice) were sampled by coccygeal venipuncture, 7 d before, and 7 and 14 d after parturition. For each sample and metabolite serum concentrations were stratified in thresholds and related to MY. When BHBA levels were high 7 d before parturition and were related to MY at d-7 postpartum, it was observed that 11.00 % of the cows lost 0.370 kg d(-1) of milk. In contrast, no relationship was observed between BHBA prepartum and MY on d-14 of lactation. It was not observed any association between high NEFA and low Ca2+ levels prepartum and MY. NEFA concentrations >= 0.5 mmol L-1 on d-7 before calving were 7.6 more susceptible for lameness incidence (P <= 0.01), and when BHBA >= 0.8 mmol L-1 cows were 2.4 times more likely to develop ketosis (P <= 0.05) in the first 60 d in milk. In brief, data indicate that a high proportion of cows are above the thresholds of beta-hydroxybutyrate and non-esterified fatty acids, and are also deficient in calcium, when determined one week before parturition. The risk thresholds for each metabolite were not associated with the amount of milk lost at d-14 after calving.