The objective of this study was to evaluate the effects of prophylactic subcutaneous (SC) Ca treatment at calving on DMI at 1 DIM, serum concentrations of Ca, P, Mg and subclinical hypocalcemia (SHC) and metritis incidence on a commercial HO herd. Cows were blocked based on parity [first (n = 143), second (n = 108) and third or greater (n = 124)], and randomly assigned to treatments after calving. Treatments were no treatment (Control; n = 190); 250 ml of 40% Ca borogluconate (CB) by SC injection at calving (1SC₂₅₀; n = 72); 500 ml of 40% CB by SC injection at calving (1SC_500; n = 63); 250 ml of 40% CB by SC injection at calving and at 12 to 18 h after the first injection (2SC_250; n = 50). Blood samples were collected immediately after calving and at 1, 2, 4, and 7 DIM. Dry matter intake was measured for 24 h after calving in individual calving pens. Intake was analyzed with GLM procedure, including treatment, parity, and their interactions in the model. Serum Ca, P and Mg were analyzed as repeated measures with mixed procedure of SAS. Metritis (foul-smelling uterine discharge with fever) and SHC (Ca ≤8.5 mg/dl) were analyzed with PROC GENMOD with binomial distributions and logit link functions including treatment, parity, Ca status (≤8.5 vs >8.5 mg/dl) and their interactions. At 1 DIM, intake was greater (P = 0.004) for 1SC₂₅₀ (13.5 kg), 1SC₅₀₀ (15.0 kg) and 2SC₂₅₀ (15.6 kg) relative to control (12.4 kg). Compared with control (8.4 mg/dl), postpartum serum Ca was greater for 1SC₂₅₀, 1SC₅₀₀ and 2SC₂₅₀ with 8.9, 9.2 and 9.0 mg/dl respectively. No treatment effect was found on serum P and Mg_. The odds of SHC were 3.7, 3.0 and 14.0 times greater (P = 0.01) for control than 1SC₂₅₀, 1SC₅₀₀ and 2SC₂₅₀ respectively. The odds to develop metritis tended to be 1.7 times higher for control than 2SC₂₅₀ (P = 0.07; 95% CI = 0.9- 3.3). These results suggest that prophylactic SC injections of Ca at calving can improve postpartum Ca status in HO cows and DMI at 1 DIM. Given the reduction on metritis and SHC with treatment, the evaluation of immune status warrant further investigation.