Prepartum management factors associated with the development of calcium imbalance during the first days postpartum in grazing dairy cows in Uruguay.

To evaluate the association between calcium (Ca) imbalance postpartum, animal-associated data, and prepartum management practices in Holstein dairy cows, we conducted a cross-sectional study based on a convenience sample of 122 dairy farms (204 primiparous and 661 multiparous cows) in Uruguay. Cows were blood sampled once between days 1 and 3 DIM after parturition for metabolite analysis. At the time of sampling, data were collected on management, housing, and feeding. To evaluate the association between Ca imbalance and animal-associated data (parity, body condition, high NEFA (non-esterified fatty acid; > 0.6 mmol/L), subclinical hypomagnesemia (Mg < 0.80 mmol/L), hypophosphatemia (P ≤ 1.4 mmol/L)), and prepartum management practices, we used multivariate logistic regression models using a serum Ca threshold of ≤ 2.00 mmol/L. Overall, 76.8 % of cows had Ca imbalance, 17 % of cows had hypophosphatemia and 31.8 % showed subclinical hypomagnesemia. The BCS (body condition score) was ≤ 2.75 in 34.4 % of cows, with 64.3 % scoring 3-3.5. Overall, 39.8 % of cows had elevated NEFA. Multiparous cows were more likely to develop Ca imbalance than primiparous cows (P < 0.05). Cows with subclinical hypomagnesemia and hypophosphatemia had higher odds for Ca imbalance. The odds were lower in summer than in autumn and winter, and higher in cows from farms without nutritional consulting service for close-up cows and without supplementation with anionic salts. Cows with prepartum access to shade were less likely to develop Ca imbalance. In conclusion, factors associated with Ca imbalance in postpartum dairy cows included other mineral imbalances, parity, inadequate prepartum nutritional management, and lack of comfort.