Subclinical hypocalcemia is a metabolic disorder characterised by a decrease in serum calcium (Ca) levels, with no clinical symptoms. The aim of this study was to determine the punctual prevalence of subclinical hypocalcemia in dairy cows, in the Sousa city micro-region, Paraíba state. Samples were collected from 29 dairy farms, consisting of 153 and 296 blood samples in the pre- and postpartum period respectively. In relation to the mineral supplementation profile, 89.25% of the properties use a commercial supplement. On average, 40.53% of lactating cows presented total serum Ca levels under the lower limit of 8.0 mg/dL, with an exclusive supplement of NaCl resulting in a higher percentage of cows, 61.11%, with the condition of subclinical hypocalcemia. For ionized Ca, the average prevalence of subclinical hypocalcemia was 21.16%. The prevalence of subclinical hypocalcemia for total serum Ca was 37.25 and 42.23% of cows in the pre- and postpartum period respectively. The type of mineral supplement did not influence (P > .05) total and ionized serum Ca levels in lactating cows. There was no significant difference (P > .05) for total and ionized serum Ca levels as a function of the reproductive period in lactating cows. Subclinical hypocalcemia was evident in the dairy cows under evaluation and occurred with an average punctual prevalence of 40.34%. Commercial supplement is the most common form of mineral mixture used; however, it was not able to promote an increase in the levels of total and ionized serum Ca levels due to errors in managing the supply.
Keywords: Dairy farming; Metabolic disorder; Mineral supplements; Semiarid; Serum calcium.