The objectives of this study were to test the effects of dietary vitamin D₃ compared with 25-hydroxyvitamin D₃ on growth and serum concentrations of vitamin D metabolites, minerals, and energy metabolites of dairy calves. Forty-five Holstein bull calves (<7 d of age) were blocked into weekly cohorts and randomly assigned to one of 5 daily supplements; control (CON, 0.25 μg of vitamin D₃/kg BW), and 2 levels (1.5 or 3 μg/kg BW) of vitamin D₃ (VitD), or 25-hydroxyvitamin D₃ (25D) added to the CON treatment resulting in the following treatment groups: CON, VitD1.5, VitD3.0, 25D1.5, 25D3.0. Calves were fed milk replacer until weaning at 56 d of age and had ad libitum access to water and starter grain throughout the experiment. Treatments were added to the milk replacer until weaning and then to starter grain thereafter. Bodyweight and blood samples were collected weekly. Data were analyzed with mixed models that included fixed effects treatment and time and random effects of calf nested within block and treatment. The CON and 25D-treated calves gained more (P < 0.05) weight from birth to weaning compared with VitD-treated calves (CON = 0.57, 25D = 0.50 VitD = 0.41 ± 0.04 kg/d), but height and feed intake did not differ between treatments. Supplementing VitD and 25D increased (P < 0.001) concentrations of 25(OH)D in serum compared with CON but the increment was greater (P < 0.01) for 25D compared with VitD (CON = 13.3, VitD1.5 = 22.9, VitD3.0 = 30.2, 25D1.5 = 40.8, 25D3.0 = 74.2 ± 4.0 ng/mL). Concentrations of Ca, P, Mg, NEFA, glucose, IgG1 and IgG2 did not differ between treatments, however, BHBA was greater (P < 0.01) in VitD and 25D supplemented calves compared with CON (CON = 0.19 VitD = 0.23 and 25D = 0.25 ± 0.02 mM). Although serum P did not differ among treatments, it tended (P = 0.08) to increase with serum 25(OH)D of calves. Feeding 25D to dairy calves was more effective at increasing serum 25(OH)D concentrations and BW gain compared with feeding VitD.