Means serum iCa concentrations for cows fed prepartum and effect of Tr1 DCAD 0.0, -100, -180 (BC1, BC2, BC3. P < 0.001) and effect of postpartum Tr2 DCAD +250 and +350 (B1A1, B1A2, B2A1, B2A2, B3A1, B3A2. P = 0.511), day P < 0.001 and interaction Tr1 x Tr2 x day P = 0.510, during experimental period.