Table 3.

Effect of supplementing ruminally protected lysine (LYS), arginine (ARG), or their combination on performance of feedlot steers

	Treatment1,2					P-value
Item	CON	ARG	LYS	LYS +ARG	SEM3	ARG	LYS	LYS × ARG
Body weight, kg
Day 0	322.7	322.2	323.1	322.4	6.75	0.92	0.97	0.99
Day 87	481.1	484.2	491.4	485.5	6.75	0.83	0.40	0.75
Day 170	622.8	625.7	622.8	619.7	6.75	0.99	0.65	0.94
Average daily gain, kg/d
Days 0 to 87	1.82	1.86	1.93	1.87	0.062	0.88	0.31	0.63
Days 88 to 170	1.66	1.68	1.66	1.55	0.062	0.44	0.27	0.41
Days 0 to 170	1.73	1.77	1.81	1.72	0.052	0.52	0.74	0.13
Dry matter intake, kg/d
Days 0 to 87	9.1	9.4	9.2	9.0	0.36	0.96	0.63	0.80
Days 88 to 170	10.6	10.3	10.0	10.0	0.36	0.77	0.14	0.45
Days 0 to 170	9.8	9.8	9.7	9.5	0.42	0.73	0.49	0.71
Gain:feed, kg/kg
Days 0 to 87	0.199	0.198	0.209	0.210	0.004	0.99	0.05	0.28
Days 88 to 170	0.157	0.168	0.168	0.156	0.004	0.91	0.86	0.26
Days 0 to 170	0.181	0.181	0.178	0.184	0.005	0.91	0.21	0.42
Days on Feed	175	174	168	175	3.7	0.67	0.73	0.58

¹Treatments were 1) a diet with no arginine or lysine supplementation (CON), 2) rumen-protected arginine (16% metabolizable arginine, Ajinomoto Heartland, Chicago, IL) top-dressed at 63 g/steer daily (ARG), 3) rumen-protected lysine (25% metabolizable lysine, AjiPro-L, Ajinomoto Heartland) top-dressed at 40 g/steer daily (LYS), and 4) a diet with both arginine and lysine top-dressed at 63 and 40 g/steer daily, respectively (ARG + LYS).

²Five pens/treatment; 5 to 6 steers/pen.

³Standard error of the mean.