The use of waste milk in a calf feeding program is suspected to contribute to the development of bacterial antimicrobial resistance. Fifty-two calves allocated in individual pens were randomly assigned to milk replacer (MR) or pasteurized waste milk (pWM) fed twice daily for 42 d and once daily from d 43 to weaning (49 d). Waste milk was picked up from a local dairy farm twice weekly during the study and tested for detection of β-lactam antibiotic class from each load of milk. Fecal swabs were taken from each calf at 5 and 8 wk of age and cultured to obtain 3 E. coli isolates per sample. Each colony was tested for its susceptibility to 12 antibiotics by disk diffusion. Feeding practice (MR or pWM) and age (5 or 8 wk) effect on E. coli antimicrobial resistance were analyzed using binary logistic regressions for each antibiotic tested. Feeding practice, calf age and interaction between treatment and age were the fixed effects of the model, calf the random effect and calf age the repeated. β-lactam antibiotic residues were detected from each pWM load. Calves fed pWM had greater probability (P < 0.05) to have ampicillin (AMP) and cephalothin (KF) (β-lactam antibiotics) resistant E. coli than calves fed MR, whereas the number of E. coli resistant to florfenicol tended (P = 0.07) to be greater in calves fed pWM than in those fed MR. However, the probability of isolating E. coli resistant to AMP and KF tended (P = 0.11; P = 0.06) to decrease in pWM from 5 to 8 wk of age, in contrast to MR calves that had similar probability of isolating E. coli resistant to AMP and KF from 5 to 8 wk of age. It is concluded that treating cows with antibiotics generates antimicrobial residues in milk and feeding calves pWM triggers the presence of resistant E. coli in the gut of dairy calves.