Our objectives were to determine (1) the effect of a single dose of an oral Ca bolus after parturition on blood Ca concentration, and (2) the effect of this supplemental Ca approach on milk production and culling. For our first objective, cows from 1 commercial dairy were enrolled within 19 h after parturition (mean ± SD = 8.3 ± 5.3 h) and randomized within parity group (1st, 2nd, and 3rd or greater) to control [CON (n = 25); no placebo] or bolus treatment [BOL (n = 25); 3 oral Ca boluses administered at once supplying 54 to 64 g of Ca (Quadrical, Biovet, Barneveld, WI)]. Blood samples were collected before group assignment and at 1, 2, 4, 8, 12, and 24 h thereafter. Plasma Ca concentration was analyzed by mixed effects repeated measures ANOVA. Cow within treatment was treated as a random effect and h postpartum, parity group, and Ca concentration at enrollment as covariates along with relevant treatment interactions. For our second objective, cows from 6 commercial dairy farms in New York State were enrolled as described for objective 1 (CON n = 1,973; BOL n = 1,976). First Dairy Herd Improvement Association test-day milk yield and culling data were collected from herd management software. We conducted a preliminary analysis using a multivariable ANOVA to analyze first test milk yield (treatment, parity group and herd as covariates) and a chi-squared test to examine the association between treatment and culling within 30 d in milk. Bolus administration did not affect mean plasma Ca concentration in the 24 h after bolus administration (CON = 2.00 ± 0.03 vs. BOL = 1.96 ± 0.03 mmol/L, P = 0.36). No preliminary associations between treatment and first test milk yield (CON = 38.1 ± 0.2 vs. BOL = 38.1 ± 0.2 kg/d, P = 0.88) or culling within 30 d in milk [CON = 4.1% (80/1,973) vs. BOL = 4.9% (96/1,976), P = 0.22] were observed. Administration of a single dose of an oral Ca bolus after parturition did not increase blood Ca concentration, and preliminary results indicate no association between treatment and early lactation milk production or culling.