‘Bull-e’ up feed efficiency of cows
By HAROLD HARPSTER
Feed efficiency has always had a huge impact on beef’s bottom line. But in times of high feed prices — which seem to be almost all the time these days — it’s especially critical.
On the surface, the concept of feed efficiency couldn’t be simpler: the feed required to produce a pound of gain. Right?
Well, the rub comes when trying to measure it on individual animals, and trying to interpret its meaning for herd selection. Most cattle are group-fed, and it takes special equipment or individual pens to individually and accurately measure feed intake.
It’s time-consuming and expensive. That’s why it has been extremely difficult to use feed efficiency in selection programs.
That’s about to change, at least for those using Angus sires. This fall, The American Angus Association and Angus Genetics Inc. began introducing Residual Average Daily Gain Expected Progeny Difference, or RADG EPD, technology with the help of electronic data management.
Yes, RADG EPD is a mouthful. But it offers potential to identify bulls that’ll produce more feed-efficient offspring after weaning.
This new EPD is made possible through genomic (DNA) technology teamed with a data bank available on Angus cattle. Much of the feed intake database was obtained from research trials conducted at University of Illinois, North Carolina State University and Iowa State University.
Bull sire summary data will now indicate the per-day advantage in average daily gain expected. You’ll find this RADG EPD value in a bull pedigree’s production section.
Bringing it home to your herd
The jargon of how the trait is calculated is hard to follow. But simple cowboy arithmetic shows the economic impact:
Let’s assume you’re considering Bull A, with a RADG EPD value of +0.10, and Bull B, with a value of – 0.10. On average, calves sired by Bull A would have an 0.20-pound-per-day advantage in average daily gain if both groups were fed the same amount of feed during the post-weaning period.
Suppose 100 calves of Bull A are feedlot-fed for 160 days and the fed market is 87 cents per pound. Calves of Bull A would return an extra $2,784 (100 calves x 160 days on feed x 0.20 pounds per day gain advantage at 87 cents per pound). That’s a $27.84-per-calf advantage for selecting a bull that passes superior feed efficiency to his offspring!
Remember, the RADG trait refers to expected differences in the performance of calves after weaning. Don’t try to use it as a cow efficiency tool.
Other traits must be examined for cow decisions. RADG provides an extra piece of selection information that can make a big impact on bull decisions and subsequent offspring performance.
For more information about AGI or other Angus Association programs, visit www.angus.org or call 816-383-5100.
Harpster is a Penn State animal scientist and a beef cow-calf producer.
How RADG EPD came about
Here’s how the experts from the American Angus Association explain RADG EPD’s development:
It began with a comprehensive genetic evaluation of phenotypic traits. Then genomic results from the Angus-specific Igenity profile were added in.
That Igenity profile was derived from a scan of the entire genetic code of an animal having 50,000 gene markers. It analyzed traits including calf weaning weight, postweaning gain, ultrasound subcutaneous fat thickness, individual calf dry-matter intake and dry-matter intake genomic values.
Weight, gain, fat and genomic pieces function as indicator traits to predict genetic feed-intake values. The resulting feed-intake EPD is used to calculate residual gain.
In this step, the genetic feed intake EPD and the genetic ultrasound fat EPD are used to adjust the postweaning gain EPD to create residual gain, or RADG. Weighting factors or regression coefficients representing genetic trait relationships are used to adjust the intake and fat EPDs.
The genetic correlation (how one trait is related to another) between the genomic value and the phenotypic dry-matter intake is 0.45 — 20% of the additive genetic variance. These genomic values provide an indicator trait for dry-matter intake. A similar scenario occurs with indicator traits of ultrasound and genomic values in the carcass EPD model.
RADG is presented in pounds per day, with a higher value being more favorable. Based on 2,315 Angus sires for which RADG EPDs were calculated, the lowest bull was -0.25 and the highest bull was +0.43.
— Harold Harpster
This article published in the November, 2010 edition of AMERICAN AGRICULTURIST.
All rights reserved. Copyright Farm Progress Cos. 2010.