Using Expected Progeny Differences EPDs in Bull Selection

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Using Expected Progeny Differences (EPDs) in Bull
Selection
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Introduction

• Expected Progeny Differences (EPD) provide
  producers with a group of selection tools that
  specifically address the genetics of an animal.

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What are EPD,s and where do they come from ?
The calculation of EPDs requires a great deal of
mathematical equations and computing power.
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What Expected Progeny Differences can do

• Use EPDs to compare animals of the same sex
  within breeds.
• When comparing two or more animals, the
  differences in their EPDs indicate the
  differences you would expect to see in their
  progeny due to genetics.
• EPDs can be used as tools to increase, decrease
  or maintain any trait for which they are
  calculated.
• EPDs can be used as one or several can be used in
  selection.
• EPDs can be used to track genetic trends within
  breeds.

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What Expected Progeny Differences can not do

• EPDs can not compare animals from different
  breeds.
• An EPD of 0 is not breed average.
• EPDs are not constant

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• EPDs do not predict direct outcomes.
• EPDs do not make up for poor management.
• EPDs do not indicate structural soundness.
• Unless EPDs are multi-breed based, they do not
  take into account hybrid vigor.

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Breed Averages and why they are important
Breed average EPDs provide a benchmark to compare
animals to.
Example Breed averages for Black Angus
calves born 2006 BW2.9 WW36 YW63
Milk14 TM32
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Genetic trends
EPDs allow breed associations to track genetic
trends within the breed.
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Accuracies
Accuracies are a way to determine how reliable an
EPD is.
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Accuracies that are close to 1 indicate that
there is more confidence that the EPD value
reflects the true genetic worth of an animal for
that trait as compared to a lower accuracy.
High accuracy would be (0.08 0.99). Low
accuracy would be (0.05 0.30).
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At times you will see an EPD that looks like
this ( I34/.05) The ( I ) stands for
interim. This means that an individual animals
raw information has not been used in the
formulation of its EPD and that the EPD was
generated from ancestors only. This is usually
the case in either very young animals, or from
herds that dont contribute to the raw data, or
the individual was the result of embryo
transplant. Embryo transplant calves will have
interim EPDs until their performance recorded
offspring are entered into the data base.
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Possible Change
An EPD is the best estimate as to the true
breeding value of an animal.
Example
A bull has a birth weight EPD of 2.5 with an
accuracy value of 0.09, it can be expected that
his EPD for birth weight could change by 0.26
lbs. The next time another genetic evaluation
is run.
Possible change tables are published as part of
the breeds sire summary.
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BLACK ANGUS POSSIBLE CHANGE TABLE  
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Percentile Ranks
Breed associations also provide percentile ranks
for their animals. These charts are a way to see
how a specific animal compares with other animals
within the breed. Breed average EPDs are
always the 50th percentile.
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Percentile Table Active Sires  
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Prairielane Ideal 0051-3011
These are his current EPDs generated by the
Canadian Angus Association
BW 1.5/.66 WW 74/.65 YW 117/.65
Milk 24 TM 60 YG27
Breed averages for Black Angus Active Sires
BW 3.0 WW 37 YW 67 Milk 15 TM 34 YG30
By comparing the breed average with 3011 you will
see the following The difference in BW EPD is(
3.0) ( 1.5 ) 1.5 you could use this bull
on heifers. The difference in WW EPD is (74)
( 37) 37 This means that you should get 37
lbs more/calf at weaning as compared to the breed
average. The difference in YW EPD is( 117) (
67) 50 lbs. more at yearling on each of his
progeny than compared to breed average.
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Types of EPDs
Theoretically, an EPD can be developed for any
quantitative trait.
Bulls, and females can have calculated EPDs, but
EPDs are most often associated with bulls. This
is mainly because

• Bulls have more progeny than cows and therefore
  usually have higher accuracies.
• There is more opportunity for selection among
  males than among females, so EPDs are of more use
  in bulls
• Bulls contribute more, genetically, to the herd
  because, as females are retained, the sires of
  these females are contributing half of their
  genetics to the cows.

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Growth Traits

• Birth Weight (BW) related to calving ease
• Weaning Weight (WW) pre weaning growth
• Yearling Weight (YW) weaning to one year of age
• Milk (M) milking and mothering ability
• Total Maternal (TM) sires daughters milking
  ability

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Reproductive Traits

• Calving Ease (CE) - the ability to successfully
  deliver a calf
• Maternal Calving Ease (MCE ) genetic part sire
  makes to his daughters
• Stayability (STAY) ability to stay in the herd
  for at least six years
• Scrotal Circumference (SC) transition ability
  for scrotal size.
• Heifer Pregnancy (R) ability for sires heifers
  to conceive prior to two years of age.

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Carcass Traits

• Rib Eye Area (REA) predicts rib eye size
• Rib Fat (FAT) fat thickness between 12th and
  13th rib
• Intramuscular Fat (IMF) refers to marbling

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How is this information used to make selections?
Example 1 Selecting a sire using Birth Weight
EPD
Sampson The Bull BW EPD 5.0 lbs.
Slim The Bull BW EPD -1.5 lbs.
Cows of similar genetic makeup
The average weight differences between the calves
would be 6.5 lbs. with Slim the bull siring the
lighter calves. We can expect that Sampsons
calves would be 6.5lbs heavier than Slims.
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Example 2 Selecting a sire using Weaning
Weight EPD
Sampson The Bull WW EPD 65lbs.
Slim The Bull BW EPD 35lbs.
Cows of similar genetic makeup
Sampsons calves will have an average weaning
weight that is 30 lbs. per head more than Slims
calves. On 100 head _at_ 1.00/lb. Sampsons calves
would return you an extra 3,000.00. This extra
income has cost you really nothing except a
little home work.
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What may be coming down the road in the future?
There is a substantial effort being made in
identifying DNA markers mainly in regards to
carcass quality.
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Summary
Expected Progeny Differences provide producers
with useful tools for their selection decisions.
Although they are very useful, they are not the
only tool available to breeders. They do not
replace visual assessment or pedigrees, but
enhance them. There is a lot of information to
sort through based on the breed and production
goals in mind. Care should be taken to narrow
down the information to only those values that
are pertinent to your operation.