More than 60 different ARGs have been found in cattle manure; tetracycline resistance genes may be the most common. A USDA-ARS study that sequenced the genome (See Fact Sheet 3.B.) of 160 antibiotic resistant E. coli and the entire fecal microbial community from 28 adult dairy cows, veal calves, and pre-weaned calves found that 61% of all identified ARGs encoded resistance to tetracycline, 20% encoded resistance to aminoglycosides, 8% to macrolides, 3% to β-lactams, 0.8% to sulfonamides, and 0.6% to trimethoprim.