Ranking intervention targets. Value of Spearman's correlation coefficient (P ⩽ 0·05) between parameter values and fraction of resistant (a) enteric E. coli or (b) E. coli in ingesta by the end of feedlot rearing, given outcome variability introduced by the other parameters of bacterial ecology. For each intervention parameter the data are from 100 model simulations. Parameters: BC, BW, BF, fractional reduction on log scale in plasmid transfer in E. coli in the enteric habitat, water in troughs or feed in bunks, respectively; TC, TW, TF, fractional death of the plasmid-donor cells in E. coli in the enteric habitat, water in troughs or feed in bunks, respectively; γ, fractional regular replacement rate of enteric E. coli; KC, KW, KF, fractional reduction (between 0 and 0·4) in maximum E. coli log c.f.u./ml enteric habitat, water in troughs or feed in bunks, respectively; KWfr, fractional reduction in E. coli log c.f.u./ml fresh water supplied; PC, PW, PF, PE, fractional plasmid curing (between 0 and 0·2) resistant E. coli in the enteric habitat, water in troughs, feed in bunks or the pen's environment, respectively.