Based on the results of multivariable regression models, the addition of 30 g of GAC to 1.5 doses (150 g of IgG) of CR did not influence passive immune transfer in newborn Holstein dairy calves as indicated by similar AEA IgG (%), STP (g/dL), and serum IgG (mg/mL) concentrations between groups at 24 h of age (Table 2;P > 0.05).