Table 7.

Milligrams per kilogram-LW and Reg/AY calculated at the feedyard level by medically important antimicrobial class.

Metric	Antimicrobial class	Number of feedyards	Year	Study level values	Feedyard level values
					Mean	SD	Median
mg/kg-LW	Aminoglycoside	1	2018	0.016	0.418	–	0.418
			2019	0.022	0.396	–	0.396
	Cephalosporin	18	2018	0.23	0.242	0.425	0.058
			2019	0.138	0.137	0.213	0.044
	Fluoroquinolone	17	2018	0.122	0.157	0.131	0.116
			2019	0.122	0.245	0.426	0.079
	Macrolide	20	2018	21.101	21.675	18.864	21.908
			2019	21.503	18.89	15.283	18.116
	Penicillin	6	2018	0.106	0.293	0.41	0.042
			2019	0.094	0.517	0.859	0.17
	Phenicol	19	2018	0.502	0.653	0.897	0.366
			2019	0.585	0.719	0.768	0.255
	Sulfonamide	8	2018	0.857	1.571	2.42	0.507
			2019	1.144	5.804	10.923	1.343
	Tetracycline	17	2018	4.952	42.061	92.672	2.425
			2019	4.795	33.448	94.161	1.359
Reg/AY	Aminoglycoside	1	2018	0.003	0.05	–	0.05
			2019	0.003	0.044	–	0.044
	Cephalosporin	18	2018	0.137	0.139	0.272	0.032
			2019	0.095	0.082	0.126	0.021
	Fluoroquinolone	17	2018	0.047	0.056	0.053	0.044
			2019	0.053	0.08	0.13	0.028
	Macrolide	20	2018	2.268	2.008	1.211	2.313
			2019	2.112	1.775	1.219	1.91
	Penicillin	6	2018	0.02	0.051	0.067	0.006
			2019	0.015	0.074	0.128	0.026
	Phenicol	19	2018	0.05	0.061	0.084	0.034
			2019	0.057	0.064	0.068	0.029
	Sulfonamide	8	2018	0.007	0.016	0.03	0.005
			2019	0.009	0.076	0.162	0.012
	Tetracycline	17	2018	0.209	1.061	2.549	0.147
			2019	0.219	0.936	2.908	0.156