A randomized clinical trial assessing the effect of the timing of the administration of oral calcium supplementation on blood calcium and magnesium concentrations after calving in dairy cows
Keywords:subclinical hypocalcemia, oral calcium, magnesium
Subclinical hypocalcemia (SCH) is an important metabolic disease of dairy cattle affecting up to 70% of multiparous cows. Blanket administration of oral calcium boluses to multiparous cows immediately postpartum is a popular management strategy to treat SCH. Recent studies, however, report that more than 60% of cows with low total blood calcium concentrations at calving have normal calcium concentrations on the second day postpartum and are high producing animals. In contrast, SCH that persists for several days is associated with impaired health and performance. Developing management strategies that delay the administration of oral Ca concentration until the second day postpartum and targeting cows with inadequate Ca homeostasis is of interest to the dairy industry. The first step in developing such strategies is to understand the differences in the dynamics of calcium (Ca) and magnesium (Mg) when oral Ca supplementation is administered at different days postpartum. Thus, our study aim was to determine the dynamics of Ca and Mg concentrations during the first 5 days in milk (DIM) following the administration of an oral Ca supplement at calving or on the second day postpartum.