Using EPDs in Selection

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Using EPDs in Selection

• Stolen and edited by Brandon Freel and Daniel
  Powell
• Originally compiled by Colorado Agriscience
  Curriculum

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Objectives

• Define Expected Progeny Difference.
• Identify terms associated with EPDs.
• Interpret EPD categories.
• Analyze EPD variations within breeds.

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You must first look at breeding values.

• Phenotype The appearance of an animal.
• Genotype What genes are present and how they
  are combined.

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How are Breeding Values Reported?

• (EPD) Expected Progeny Difference A
  measurement of genetic potential based on the
  performance of relatives.
• (ACC) Accuracy is an important term used in
  understanding EPDs. It is a measure of expected
  change in the EPD as additional young are born to
  the sire. A high accuracy value is better as the
  chances of the EPD being correct rise.

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How are Breeding Values Reported?

• Common EPDs Performance-based, Carcass-based,
  and Ultrasound.
• Performance-based EPDs Are based on a
  measurement of how well the bulls offspring
  perform. Examples of performance-based EPDs are
  birth weight, weaning weight, milk and yearling
  weight.
• Carcass-based Are based on how well the bulls
  offspring have performed on the rail. Examples
  of carcass-based EPDs are Rib-eye Area, Fat
  (Outer), Retail Product, and Intramuscular Fat.
• Ultrasound EPDs Done from an ultrasound of the
  actual bull. Examples of ultrasound EPs are
  Rib-eye Area, Fat (Outer), and Retail Product.

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How to Compare EPDs
BW WW Milk YW Marb REA FAT IMF RE FAT RP
Bull A -0.5 61 15 111 .20 .19 .017 .50 .22 .004 .28
Bull B 0.1 50 21 51 .20 .44 .017 .26 .66 -.046 .28

• EPDs can be useful for comparison. Look at the
  Select Sires Explanation for how EPDs are
  measured. For example Birth Weight is in pounds.

How much more will Bull B weigh at birth than
Bull A? Answer .6 pounds. How much more will
bull A weigh at weaning than Bull B? Answer
11 pounds Which bull would be a better bull for
heifers? Answer Both would be fine. But
smaller calves would come from A. Which bull has
a bigger Rib-eye Area? Answer Bull B
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Selection of Cows

• Culling Cows should be culled from the herd
  based on the productivity of their calves.
• Evaluation Cows should be culled based on
  evaluation of the udders, eyes, skeleton and
  teeth.

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Selection of Heifers

• Try to select heifers that will conceive early in
  the breeding season, calve easily, produce a good
  supply of milk, wean a heavy calf, make a
  desirable genetic contribution to your cow herd,
  and have calves with desirable carcass traits.

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Accuracy

• The reliability that can be placed on the EPD.
  Accuracy of close to 1.0 indicates higher
  reliability.

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Herd

• Indicate the number of herds from which daughters
  are reported.

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Birth Weight

• Predictor of a sires ability to transmit birth
  weight to his progeny, compared to the progeny of
  an average bull for a specific breed expressed
  in pounds.

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Weaning Weight

• Predictor of a sire's ability to transmit
  weaning growth to his progeny, compared to the
  progeny of an average bull for a specific breed
  expressed in pounds.

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Yearling Weight

• Predictor of a sire's ability to transmit
  yearling weight, compared to the progeny of an
  average sire for a specific breed expressed in
  pounds.

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Maternal Milk

• Predictor of a sire's genetic merit for that
  part of weaning weight attributed to milk and
  mothering ability. It is compared to daughters of
  an average bull for a specific breed.

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Scrotal Circumference

• Predictor of the difference in transmitting
  ability for scrotal size, compared to the progeny
  of an average bull for a specific breed
  expressed in centimeters.

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Objectives

• Define Expected Progeny Difference.
• Identify terms associated with EPDs.
• Interpret EPD categories.
• Analyze EPD variations within breeds.