Posted February 18, 2025
RAAA has a project underway with the University of Wyoming. The first year of this effort compared two young Red Angus sires that showed significant differences in their growth traits. During February and March 2024, 24 progeny were born to randomly-mated university females by these two sires. Of the 24, 11 were sired by the high-growth bull (Sire 1), and the remaining 13 by the lower-growth sire (Sire 2). Both bulls are young and unproven, with no progeny records in the RAAA database. However, they both have genomically enhanced EPDs, reflecting higher accuracy levels from genotyping.
Comparison of the Two Bulls’ WW and YW EPDs:
Sire 1’s WW EPD is 35 lbs. higher than Sire 2’s WW EPD
Sire 1’s YW EPD is 84 lbs. higher than Sire 2’s YW EPD
Weaning and Early Growth Data
The calves in this project were weaned in early October and grown on a high-roughage ration at the University of Wyoming research center near Laramie. They were weighed individually on Jan. 20 at an average age of 328 days – well after weaning but before one year of age. Given the differences in the two sires’ EPDs, we would expect the actual weight difference in these “short yearling” cattle to fall between 35 and 84 lbs.
Actual Weight Difference
After adjusting for calf sex and age, the observed weight difference between the two sire groups was 47 lbs. – favoring calves sired by the higher-growth bull. On a steer–equivalent, age-constant basis, calves by Sire 1 averaged 772 lbs., while progeny of Sire 2 weighed 725 lbs. At today’s market prices, the value difference between the two sire groups is approximately $125 per head, purely due to sire genetic differences.
This comparison illustrates that Red Angus EPDs are effective. Genetic differences “on paper” do indeed translate to real-world phenotype differences. Using EPDs to achieve better cattle performance is that straightforward.
