Feed intake and efficiency of growth are
economically important traits of beef cattle. This study
determined the relationships of daily DMI, feed:gain
ratio [F:G, which is the reciprocal of the efficiency of
gain (G:F) and therefore increases as the efficiency of
gain decreases and vice versa, residual feed intake
(RFI), and partial efficiency of growth (efficiency of
ADG, PEG) with growth and carcass merit of beef cattle.
Residual feed intake was calculated from phenotypic
regression (RFIp) or genetic regression (RFIg) of ADG
and metabolic BW on DMI. An F1 half-sib pedigree
file containing 28 sires, 321 dams, and 464 progeny
produced from crosses between Alberta Hybrid cows
and Angus, Charolais, or Alberta Hybrid bulls was
used. Families averaged 20 progeny per sire (range =
3 to 56). Performance, ultrasound, and DMI data was
available on all progeny, of which 381 had carcass data.
Phenotypic and genetic parameters were obtained using
SAS and ASREML software, respectively. Differences
in RFIp and RFIg, respectively, between the most
and least efficient steers (i.e., steers with the lowest
PEG) were 5.59 and 6.84 kg of DM/d.