Feed Efficiency and its Measurement

Providing feed is a major input cost in beef production, hence improvements in the efficiency of feed utilization will reduce the cost of production.

Residual feed intake (RFI) is a measure of Feed Efficiency, and is defined as the difference between an animal’s actual feed intake and its expected feed intake, based on its size and growth. It is independent of the level of production, and the lower the value the more efficient the animal is.

Available information indicates that postweaning RFI is moderately heritable, and that selection for low RFI will result in progeny that consume less feed for the same level of production as progeny of high RFI cattle.

BREEDPLAN produces two EBVs relating to Feed Efficiency – Net Feed Intake (Post Weaning) and Net Feed Intake (Feedlot Finishing). Both EBVs are calculated from information collected in feed efficiency trials. Whilst there is a positive relationship between the two EBVs, some animals do rank differently for feed efficiency in the two different scenarios.

(i) Net Feed Intake (Post Weaning)

NFI-P EBVs are estimates of genetic differences between animals in feed intake at a standard weight and rate of weight gain when animals are in a growing phase. For example, animals placed in a feedlot post weaning. NFI-P EBVs are expressed as kilograms (kg) of feed intake per day.

Lower, or more negative, NFI-P EBVs are more favorable. For example, a bull with a NFI-P EBV of –0.7 kg/day would be expected to produce progeny that eat less feed per day than the progeny from a bull that has a NFI-P EBV of +0.5 kg/day (when the progeny are of similar weight, are growing at a similar rate, and are in a growing phase).

(ii) Net Feed Intake (Feedlot Finishing)

NFI-F EBVs are estimates of genetic differences between animals in feed intake at a standard weight and rate of weight gain when animals are in a feedlot finishing phase. NFI-F EBVs are expressed as kilograms (kg) of feed intake per day.

Lower, or more negative, NFI-F EBVs are more favorable. For example, a bull with a NFI-F EBV of –0.6 kg/day would be expected to produce progeny that eat less feed per day than the progeny from a bull that has a NFI-F EBV of +0.8 kg/day (when the progeny are of similar weight, are growing at a similar rate, and are in a feedlot finishing phase).

Literature Cited:

Residual feed intake in beef cattle – J P.F. Arthur, R.M. Herd
Understanding Net Feed Intake EBVs – BREEDPLAN