An increase in antimicrobial-resistant (AMR) bacteria threatens effective treatment for human and animal diseases. To combat this problem, we must identify and manage sources of these bacteria; one of these sources is agriculture. Young dairy calves are likely reservoirs of multi-drug resistant (MDR) Escherichia coli and AMR genes because they carry a higher proportion of fecal resistant and MDR E. coli compared to other cattle on dairy farms. Among MDR E. coli from dairy calves, AMR genes have been found co-located with iron scavenging genes. The optimum iron concentration for in vitro E. coli growth is lower than the iron concentration of whole milk, the primary diet of dairy calves. We hypothesize that this low iron diet creates an environment that induces selection for E. coli carrying iron scavenging genes, which then induces co-selection for AMR genes as well. To test this hypothesis, 20 calves were assigned to two dietary groups that received either milk replacer (CTRL) or milk replacer supplemented with iron at 1600ppm dry matter (IRON). Fecal samples were collected at least weekly through 42 days of age to measure fecal iron content. Blood samples were drawn weekly to determine serum iron and total iron binding content. Fecal iron content for pooled samples in IRON calves remained higher (median 9137 ppm DM) than in CTRL (median 704 ppm DM) throughout the study. Serum iron was higher in the IRON group throughout the study (p<0.0001). Serum total iron binding content was higher in CTRL calves (p<0.0001) and increased as the calves aged (p<0.05). These results indicate no adverse effects of iron supplementation at this level. In both groups, as the calves aged, the number of antibiotic classes they were resistant to decreased, as is expected based on previous studies. Evidence indicates no co-selection of AMR genes since there was no difference in the number of AMR classes between the CTRL and IRON groups. However, the CTRL diet exceeded optimal iron for fecal E. coli growth and was higher than a whole-milk diet, which suggests iron scavenging genes were not beneficial to E. coli within the fecal environment. Further research on the effects of a whole milk diet could identify evidence of co-selection. Should iron supplementation of milk replacers be successful in reducing fecal AMR in young calves, it could serve as an affordable antibiotic stewardship intervention for dairy producers.