RFI Raw Data for

D Bulls

Here is the raw data on our Lilybrook D bulls of the Canadian Hereford Association’s Residual Feed Efficiency Trial number #9 (Nov 9, 2016 to Feb 1, 2017) as well as the RFI EPD and PWG

Feed efficiency (RFI, RG, RIG) values have been calculated across contemporary groups (pens in this case), however bulls at this time can only be compared within pen. Comparison across pens can be conducted when estimated breeding values (EBVs) have been calculated. 

RFIFAT_A refers to residual feed intake adjusted for final off-test backfat thickness and has been calculated across contemporary groups. It is expressed in kg DM/day and can be converted to lb DM/day by multiplying the value by 2.2046. Negative RFI means superior feed efficiency compared to a positive bull.

 RGFAT_A refers to residual gain adjusted for final off-test backfat thickness and has been calculated across contemporary groups. It is expressed in kg gain/day and can be converted to lb/day by multiplying the value by 2.2046. it identifies bulls with superior growth potential and positive values have superior growth to negative values.

 RIGFAT_A refers to residual intake and gain adjusted for final off-test backfat thickness and has been calculated across contemporary groups. It is expressed in Standard deviations above the mean. Positive RIG values means superior feed efficiency and superior growth compared to a bull with negative RIG values.

 RIGFAT_A is perhaps the most meaningful data point to consider at this point in the project as it represents the residual feed intake AND the residual gain. In other words this represents animals with lower feed intake but are also high gainers. In this instance, the more positive the number the better.

The following is copied from the CHA website (http://www.hereford.ca/3_performance/EPD%20Averages%20Tools%20and%20Trends%20FALL%202017.pdf , copied Jan 06, 2018)

Residual Feed Intake (RFI)
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. The EPD is expressed as an RFI score, with a larger values equating to greater efficiency.

Interpreting the RFI score
The AVERAGE animal in the CHA dataset has an RFI score of 100. The current population average (calves born in the last 2 years) is 101.4. The average values for the EPD will change as data is collected and EPDs are updated, so remain aware of the EPD average for Hereford cattle. A one-point change in RFI score represents 10 pounds of feed per year, and a larger number on the scale indicates the animal is more efficient. For more efficient bulls whose progeny eat less than expected, their index values are larger. For example: a bull whose progeny will eat 10 lbs less over the year than we would expect would score 101, where the expected intake is based on growth and weight of the animal. A bull whose progeny will eat 200 lbs less over the year than expected will have a score of 120. For less efficient bulls whose progeny eat more than expected, their index values are lower. Where a bull’s progeny that eats 10 pounds more than expected over a year will have an index of 99 and a bull’s progeny that eats 200 lbs more a year will score 80.

Post Weaning Gain (PWG)
As RFI is strictly a measure of efficiency it is important to balance this trait with gain. To ensure producers are able to select efficient cattle that still have the ability to gain, the CHA is introducing a Post Weaning Gain (PWG) EPD that is simply WW EPD subtracted from YW EPD. This value is expressed in expected post weaning pounds of gain; the difference between yearling and weaning. The current population (animals born in the last 2 years) average for PWG is 30.7.

Last updated: Jan 06, 2018

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