Table 4.

Growth performance, liver abscesses, and carcass traits of feedlot cattle from cattle fed tylosin for the FIRST-78%, LAST-75%, or continuously (CON) during the feeding period.

Item	Treatmentsa				P-values
	FIRST-78	LAST-75	CON	SEM	FIRST-78 vs. CON	LAST-75 vs. CON
No. of cattle	2,525	2,526	2,525
Growthb
Initial Hip Height (m)	1.2	1.2	1.2	0.01	0.51	0.39
Initial BW (kg)	393.5	395.2	393.6	5.49	0.99	0.22
Final BW (kg)	681.0	680.0	677.5	9.25	0.25	0.40
DMI (kg/d)	11.9	11.9	11.8	0.14	0.80	0.22
ADG (kg/d)	1.8	1.8	1.7	0.03	0.25	0.69
F:G	6.7	6.8	6.8	0.07	0.23	0.70
Total liver abscesses(%)	61.0	64.2	61.9	0.4	0.81	0.53
Liver Scorec
0 (%)	39.0	35.9	38.1	3.64	0.81	0.53
A (%)	37.5	41.2	42.1	3.53	0.23	0.82
A+ (%)	23.5	23.0	19.8	3.92	0.05	0.08
Carcass Traits
Carcass Weight (kg)	410.2	408.1	406.9	5.72	0.04	0.45
Dress Percentage (%)	60.2	60.0	60.1	0.1	0.20	0.61
Yield Grade
Canada 1 (%)	21.9	21.6	20.9	3.91	0.74	0.82
Canada 2 (%)	35.9	39.2	39.0	2.11	0.11	0.92
Canada 3 (%)	42.2	39.3	40.2	5.35	0.55	0.80
Quality Grades
Canada Prime (%)	1.0	0.8	1.2	0.25	0.62	0.25
Canada AAA (%)	69.2	64.4	66.7	2.69	0.31	0.35
Canada AA (%)	25.8	30.4	27.3	2.72	0.48	0.16
Canada A (%)	0.6	0.8	1.0	0.24	0.09	0.43
B4 (%)	3.3	3.4	3.6	1.33	0.75	0.80
Other (%)d	0.1	0.2	0.2	0.11	0.59	0.62

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

^bDMI, dry matter intake; ADG, average daily gain; F:G, feed-to-gain ratio, calculated as DMI divided by ADG (live weight basis).

^cLiver score 0 = no abscesses (normal healthy liver); A = 1 or 2 small active abscesses/scars or up to 4 well organized abscesses >1 inch (2.5 cm) in diameter. A+ = 1 or more large active abscesses with surrounding zone of inflammation or more than 4 small/old abscesses >1 inch (2.5 cm) in diameter.

^dCanada quality grades B2, B3, D2, D3, and E were combined into “Other” off grades category.