Blood ß-hydroxybutyrate concentrations and early lactation management strategies on pasture-based dairy farms in Colombia.

The increasing global demand for food requires sustainable solutions to close the gap in agricultural yield between industrialized and non-industrialized countries. Our objectives in this cross-sectional study were to: 1) characterize farm populations, milk yield, and early lactation management strategies of dairy cows in three different regions of Colombia, and 2) determine the association of these management strategies with blood ß-hydroxybutyrate (BHB) concentrations in the first 42 days in milk (DIM). Dairy herds (n = 56) in the Antioquia, Caldas, and Cundinamarca regions of Colombia were visited once from May through July 2018. A survey was administered to farm owners to collect demographic, management, and herd nutrition information. Blood samples from dairy cows (n = 880) between calving and 42 DIM were used to measure blood BHB concentration. Associations between management and nutritional strategies and blood BHB concentration were examined using mixed models. Prevalence of hyperketonemia was calculated as the number of samples with BHB concentration ≥1.2 mmol/L divided by the total number of samples. The estimated diet composition for early lactation dairy cows was 65.5% pasture and 31.8% commercial concentrates. The farm median milk yield, protein concentration, and fat concentration were 21.0 kg (range = 13.1-36 kg), 3.2% (range = 2.7-4.1%), and 3.5% (range = 3.0-4.1%), respectively. Milk yield least squares means (95% confidence interval; CI) differed by region: 21.7 (20.3, 23.2), 18.5 (17.0, 20.2), and 20.3 (18.5, 22.4) kg in Antioquia, Caldas, and Cundinamarca, respectively. Median blood BHB concentration was 0.5 and ranged from 0.1-4.4 mmol/L; blood BHB concentration was not different among the three regions. Pasture fertilization, increased parity, and BCS were associated with changes in blood BHB concentration. The overall prevalence of hyperketonemia was 4.5%. Geographical region affected the prevalence of hyperketonemia at 2.5%, 4.0%, and 10.2% in Antioquia, Caldas, and Cundinamarca, respectively. Mean stocking density (95% CI) was greater in Cundinamarca than Antioquia or Caldas at 3.3 (2.2, 5.0), 2.8 (2.1, 3.9) and 1.7 (1.2, 2.6) animals per ha, respectively, and was associated with hyperketonemia prevalence. Farms that abruptly stop milking cows at dry-off had 80% of the hyperketonemia events in the study. Pasture-based dairies in Colombia had lower blood BHB concentrations and estimated milk yield compared with confined production systems in temperate zones. However, geographical region, stocking density, and abrupt cessation of milking at dry-off were associated with prevalence of hyperketonemia in pasture-based dairies.