Table 3.

The effects of RFI classification on performance, feed efficiency, and ultrasound traits in steers fed a high-concentrate diet

Trait1	Low RFI	Medium RFI	High RFI	SE	P-value
No. of animals	147	199	152
Performance traits:
Initial age, d	290	290	290	9	0.908
Initial BW, kg	308	310	310	35	0.827
Final BW, kg	428	430	429	28	0.864
ADG, kg/d	1.72	1.72	1.70	0.11	0.570
Initial hip height, cm	122	122	121	3	0.136
DMI, kg/d	9.2a	10.2b	11.0c	0.2	<0.001
DMI RMSE, kg/d	2.18a	2.28b	2.42c	0.08	0.033
Feed efficiency traits:
RFI, kg/d	0.911a	0.009b	0.880c	0.030	<0.001
RG, g/d	59.09a	9.76b	−68.29c	11.53	<0.001
G:F	0.187a	0.170b	0.155c	0.014	<0.001
Ultrasound traits:
Initial backfat depth, cm	0.370a	0.394ab	0.407b	0.109	0.013
Final backfat depth, cm	0.648a	0.734b	0.758b	0.085	<0.001
Initial intramuscular fat,%	2.91	2.82	2.82	0.26	0.198
Final intramuscular fat,%	3.05	3.18	3.21	0.23	0.054
Initial LM area, cm2	20.4	20.6	20.2	1.3	0.348
Final LM area, cm2	26.2	25.9	25.8	1.0	0.415

¹DMI RMSE = day-to-day variation in DMI during the trial.

^a–cMeans within row with different superscripts differ (P < 0.05).