Table 1.

Enterococci counts of the total population and Ery^R enterococci isolated from feedlot cattle feces from cattle fed tylosin for the FIRST-78%, LAST-75%, or continuously (CON) during the feeding period.

Itema	Treatmentsb			SEM	P–valuec
	FIRST-78	LAST-75	CON		T	D	T × D
No. of Enterococci (log10 CFU/g feces)
Day 0	6.0	6.5	6.2	0.24	0.14	<0.01	0.12
Day 81	5.2	5.7	5.9
Day 160	5.3	5.3	5.3
No. of EryR Enterococci (log10 CFU/g feces)
Day 0	4.4	4.5	4.9	0.41	0.18	0.02	0.98
Day 81	5.0	5.4	5.4
Day 160	4.5	4.7	4.9

^aCattle were sampled upon arrival and after 81 and 160 days on feed. Total enterococci were enumerated on BEA, bile esculin azide agar; and erythromycin resistant (Ery^R) enterococci were enumerated on BEA^E amended with erythromycin (8 μg/ml).

^bTylosin inclusion at 11 ppm; FIRST-78% = tylosin in-feed from 0 to 125 days; LAST-75% = tylosin in-feed from d 41 to d 161; CON, control, continuous feeding of tylosin (0–161 days).

^cT, Treatment; D, Days on feed; T × D, Treatment × Days on feed.