What is an EPD?
• Expected Progeny Difference
• “the differences in performance
expected from the offspring of
one individual compared to the
offspring of another individual,
within the same breed”
Ensminger and Perry, 1997
Birth Weight EPD
• Indicates calving ease
• Measured in pounds of calf
• Expected birth weight
difference of calves,
excluding maternal influence
Johnson, 1997
Weaning Weight EPD
• Indicates growth performance at
weaning (205 day weight)
• Measured in pounds of calf
Johnson, 1997
Yearling Weight EPD
• Indicates post-weaning
performance (365 day weight)
• Measured in pounds of calf
Johnson, 1997
Milk EPD
• Measured in pounds of
weaning weight produced by
daughters
• Excludes genetics for growth
Johnson, 1997
Total Maternal EPD
• Calculated as follows:
1/2 weaning weight EPD
+
all of the milk
Total Maternal EPD
Johnson, 1997
Scrotal Circumference EPD
• Measured in centimeters
• Indicates fertility and age at
puberty of offspring
Johnson, 1997
Carcass EPDs
• Carcass Weight (Pounds of
carcass)
• Marbling (USDA marbling
degrees)
• Ribeye Area (Square inches)
• Fat thickness (Inches)
Johnson, 1997
Accuracy
• Measures reliability of EPDs.
• Young animals without a lot
of offspring have lower
accuracy
• Animals with lots of offspring
will have higher accuracy
Johnson, 1997
EPD Cautions
• Not comparable between
breeds, only within a breed
• Average breed EPDs do not
equal zero, look them up in
latest sire summary for the
breed
Johnson, 1997
EPD Cautions
• EPDs do NOT predict
absolute performance
• The biggest is not always the
best - use to fit animals to the
environment (scenario)
–Examples - milk and growth
Johnson, 1997
Breed Average EPDs
Breed
BW WW
YW
Milk
SC
Angus
+3.0
+30
+53
+12
+.08
Charolais
+1.9
+14
+24
+7
N/A
Hereford
+4.1
+33
+56
+9
+0.4
Gelbvieh
+2.3
+34
+59
+18
+0.1
Limousin
+1.2
+9
+17
+3
+0.1
Simmental
+4.2
+36
+53
+8
N/A
Johnson, 1997