Serum Ionised Calcium and Ionised Magnesium in Dairy Cows and Their Associations With the Incidence and Severity of Postpartum Metritis.

Peripartum is a critical period for dairy cows during which they may undergo postpartum diseases such as hypocalcaemia and metritis. Determination of serum total calcium (tCa) is widely used to monitor imbalances in this period, but determination of total magnesium (tMg) and ionised forms of both cations (iCa and iMg) has been less studied. In the present work, 42 healthy cows and 53 cows diagnosed with mild or moderate metritis were included. Serum samples were collected 10 days prepartum and 1, 3 and 10 days postpartum to determine tCa, iCa, tMg and iMg concentrations, as well as their corresponding ratios. Our results show that hypocalcaemia and hypermagnesaemia occur on Day 1 postpartum in cows that stayed healthy and cows undergoing metritis. Cows with moderate metritis showed lower serum concentrations of iCa and iMg throughout the period. Low values of prepartum iCa and iMg at 10 days before calving were associated with later development of metritis and therefore could represent potential prognostic indicators. In conclusion, the determination of iCa, tMg and iMg in serum, in addition to tCa, could offer a more comprehensive view of the ionic status of the periparturient dairy cow and may provide information about the risk of suffering uterine diseases.