Successful passive transfer of antibodies in neonatal calves can be achieved by feeding maternal colostrum (MC) or colostrum replacer (CR). An alternative could be a supplemented low-quality maternal colostrum (CS). The objective of this study was to determine if a commercial colostrum product (Premolac PLUS Bovine IgG, Zinpro Corporation, Eden Prairie, MN) fed to replace or supplement MC could lead to adequate IgG levels and apparent efficiency of absorption (AEA) 24 h after birth in neonatal dairy calves. Holstein calves (n = 20/treatment; TRT) were separated from their dam after birth and randomly assigned to 1 of 2 levels of CR (110 g or 150 g of IgG), low-quality colostrum (41 g IgG/L) supplemented with CR (154 g IgG fed) or MC (106 g IgG/L; 401 g IgG fed; positive control) within 1.5 h of birth. Colostrum was obtained from first (MC TRT) or second and third milking (CS TRT) of cows from The Pennsylvania State University dairy. Then, it was pooled in 2 batches and analyzed for total IgG concentration using radial immunodiffusion. Blood samples were taken before feeding colostrum and 24 h after birth and analyzed for serum total protein, total IgG, hematocrit, and Brix. In the statistical model, data were analyzed as a completely randomized design. Hematocrit was tested as a covariate but not used in the final model. Reported means are followed by their standard errors. Feeding 150 g of IgG in CR led to higher 24 h serum IgG values than feeding 110 g of IgG (16.90 ± 1.09 and 12.79 ± 1.08 mg/mL, respectively; P < 0.01). MC had higher 24 h IgG values than CS (27.04 ± 1.07 and 22.33 ± 1.08 mg/mL, respectively; P < 0.01). Serum IgG levels were statistically different between CR and MC (P < 0.01), but both had average values above 10 mg/mL IgG. Calves fed CS had greater AEA than calves fed MC (54.58 ± 2.39 and 24.38 ± 2.36%, respectively; P < 0.01). Among calves fed CR with 110 g or 150 g of IgG, AEA was not different (P = 0.68), but was greater than previous reports (40.47 and 40.09%, respectively). Total protein and Brix had a strong correlation (r = 0.98, P < 0.01). These results indicate that CR can be an alternative to MC or a supplement to colostrum with low IgG.