Relationship between residual feed intake and end product palatability in longissimus steaks from steers sired by Angus bulls divergent for intramuscular fat expected progeny difference1

The relationship between residual feed intake (RFI) and end product quality was evaluated in 133 steers from 5 Angus sires with low, moderate, or high percent intramuscular fat EPD. Steers (320.1 ± 35.76 kg) were evaluated for RFI during a 70- to 84-d growing period and classified into 3 groups based on RFI: efficient (less than -0.5 SD below the mean; n = 41), marginal (± 0.5 SD from the mean; n = 48), and inefficient (> 0.5 SD above the mean; n = 44). There were no differences among RFI groups for ADG, BW, fat thickness, carcass weight, YG, QG, or palatability traits. Inefficient steers had greater (P < 0.01) DMI than did marginal and efficient steers, and marginal steers had greater DMI (P < 0.01) compared with efficient steers. Marbling was greater (P < 0.01) in inefficient steers than in efficient steers, and inefficient steers had greater (P < 0.05) marbling compared with marginal steers. However, of all traits evaluated, RFI was only correlated with DMI (r = 0.57; P < 0.0001), feed conversion ratio (r = 0.48; P < 0.0001), marbling (r = 0.26; P < 0.01), and QG (r = 0.27; P < 0.01). Data suggest that feed efficiency in steer progeny of Angus sires divergent for intramuscular fat EPD is not related to carcass characteristics, with the possible exception of marbling score. However, due to the absence of a relationship between RFI and sensory traits, and the potential for a sire effect, it does not appear that end product quality attributes are related to feed efficiency.