Using Expected Progeny Differences (EPDs) in a Breeding Program

EPDs are one of the most effective tools available for improving the genetic quality of beef cattle. They help producers predict how the future progeny of one animal will perform relative to another. To use EPDs effectively, producers must understand how they are calculated, how to interpret them, and how they relate to specific breeding goals.
 
1. What EPDs Represent
EPDs estimate the genetic merit an animal will pass on to its offspring for traits such as:
  • Birth weight
  • Weaning weight
  • Yearling weight
  • Milk (maternal performance)
  • Carcass traits and other breed‑specific EPDs
EPDs do not describe the animal’s actual performance—they predict how its calves will perform compared to calves sired by another bull.
 
2. Three Essential Questions Before Using an EPD
1. Who calculated the EPD?
  • Some breeds publish North American EPDs, combining U.S. and Canadian data.
  • Others publish separate Canadian and U.S. EPDs due to limited genetic linkage.
  • EPDs from different countries or different breeds cannot be compared unless specifically stated as joint evaluations.
 
2. What is the breed average?
  • A positive EPD is not automatically above average.
  • Many breeds use a fixed base, so the breed average shifts yearly.
  • Comparing a bull’s EPD directly to the current breed average is essential.
Example (Bull “Enigma”):
If breed averages are BW 3.3, WW 9.4, YW 47.0, Milk 9.1:
  • Enigma is average for birth weight, weaning weight, and milk
  • Enigma is far below average for yearling weight
  • This makes him suitable for producing moderate replacement females, but not ideal as a terminal sire
 
3. What is the accuracy of the EPD?
Accuracy (ACC) ranges from 0.0 to 1.0:
  • Low ACC (<0.30): Early estimate, may change significantly
  • Moderate ACC (0.30–0.60): Includes individual performance data
  • High ACC (>0.70): Proven performance with many progeny; values are stable
As bulls sire calves, EPDs adjust and accuracy increases.
Example progression:
  • At birth: EPD +15, ACC 0.10
  • After weaning: EPD +11, ACC 0.25
  • After ~40 progeny: EPD +12, ACC 0.70
Accuracy matters because it indicates reliability.
 
3. Using EPDs in a Breeding Program
Step 1. Identify traits affecting your bottom line
Priorities differ based on marketing strategy:
Calves sold at weaning:
  • Birth weight, weaning weight
  • Maternal traits if keeping replacements
Calves sold as yearlings:
  • Birth weight, yearling weight
  • Maternal traits if retaining daughters
Retained ownership to slaughter:
  • Birth weight, carcass traits
  • Maternal traits if keeping heifers
 
Step 2. Avoid single-trait selection
  • Extreme selection for one trait (e.g., rapid growth) may worsen others (e.g., birth weight, calving ease).
  • Also evaluate soundness, temperament, feet, and conformation, which are not captured by EPDs.
 
Step 3. Evaluate your herd
Decide which traits require improvement:
  • Lower birth weights?
  • Smaller mature cow size?
  • Improved milk or stayability?
Accurate records are essential.
 
Step 4. Select the appropriate breed
  • Crossbreeding enhances low‑heritability traits (fertility, longevity) through hybrid vigor.
  • Moderate breeds often excel in maternal traits.
  • Large-framed breeds generally excel in growth traits.
 
Step 5. Select the bull within that breed that meets your goals
  • Choose bulls with EPDs aligning with your production objectives.
  • For complex breeding goals (growth + maternal + carcass):
    • Use a balanced bull or
    • Split the herd:
      • Maternal sire → replacement females
      • Terminal sire → feeder/slaughter calves
 
4. Breed Average EPD Values (Common North American Breeds)
Breed
Country
Birth Wt
Weaning Wt
Yearling Wt
Milk
Angus (Red)
Canada
+1.30
+27.00
+45.00
+11.0
Angus (Black)
Canada
+3.20
+32.00
+58.00
+13.0
Hereford
North America
+3.90
+37.00
+62.00
+14.0
Charolais
North America
+1.47
+18.65
+32.78
+5.59
Simmental
North America
+3.10
+35.30
+58.30
+7.30
Limousin
North America
+2.60
+34.60
+64.90
+17.2
Note: EPDs cannot be compared across breeds.