TABLE 1.

Initial concentrations of total and antibiotic-resistant E. coli and enterococci in open feedlot pen scrapings and in the bulking agent for both cycles of the study

Cycle and sample type	Initial concn (log CFU g−1 [wet wt])
	Total E. coli	AzithromycinR E. coli	TetracyclineR E. coli	Total enterococci	TylosinR enterococci	TetracyclineR enterococci
Winter-spring
Pen scrapings	7.63	BDLa	BDL	11.63	1.38	2.63
Corn stalk residues	4.15	4.30	BDL	4.34	BDL	3.30
Summer-fall
Pen scrapings	BDL	BDL	BDL	3.78	BDL	BDL
Rye silage	BDL	BDL	BDL	4.93	BDL	BDL

^aBDL, below detection limit.