Genetic Evaluations

1
Genetic Evaluations Decision Support to
Improve Feed Efficiency

• Dorian Garrick
• Department of Animal Sciences
• Colorado State University

2
Knee-Jerk Logic

• Natural to think we should strive to become more
  efficient producers
• We have been indoctrinated into using EPDs as
  tools to aid selection
• Use WWD EPDs to increase weaning weight
• CED EPDs to increase ease of calving
• Therefore natural to want efficiency EPDs to
  become more efficient

3
Animal Breeding
Breeding Objective
Goal
Selection Criteria
Economic Analysis
Breeding SchemeDesign
Mating Plan
Dissemination System
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Goal

• Cow-Calf
• (Future) profit from sale of weanlings produced
  from grazed (otherwise low-value) forage while
  enhancing wildlife and environmental factors
• Ranch is the unit of interest
• Feedlot
• (Future) profit from finishing a pen or line of
  weanlings
• considering food safety, environment, human
  health
• Pen is the unit of interest

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What do you do with the Goal?

• Define the breeding or selection objective
• List of traits that (directly) influence the goal
• The relative emphasis of each trait in the list

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List of Traits

• Most producers can define this list more easily
  than the goal
• Suppose our list includes
• Outputs (eg total sale weight)
• Inputs (eg purchased feed)
• Efficiency (eg lbs net sale weight/lbs feed)
• This list dictates the EPDs we desire

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Index Approach

• Simultaneously consider the EPDs for each trait
  in the list in terms of their contribution to our
  goal (profit)
• INDEX r1EPDwt - r2EPDfeed r3EPDeffic

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Relative Trait Emphasis

• Relative Economic Value (REV)
• Value of a unit change in that trait, all other
  traits in the list held constant
• Separately calculate this value for sale weight,
  feed requirements, and efficiency

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REV for Sale Weight

• What is the value (increased profit) from a
  unit change in sale weight, with no changes in
  the other traits in our objective (ie feed
  requirements or feed efficiency)?

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REV for Sale Weight

• What is the value (increased profit) from a
  unit change in sale weight, with no changes in
  the other traits in our objective (ie feed
  requirements or feed efficiency)?
• The answer is the sale price

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Index Approach

• INDEX (beef price) EPDwt - r2EPDfeed
  r3EPDeffic

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REV Feed Intake

• What is the value (increased profit) from a
  unit change in feed requirements, with no changes
  in the other traits in our objective (ie sale
  weight or feed efficiency)?

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REV Feed Intake

• What is the value (increased profit) from a
  unit change in feed requirements, with no changes
  in the other traits in our objective (ie sale
  weight or feed efficiency)?
• The answer is the feed price

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Index Approach

• INDEX (beef price) EPDwt - (feed cost)
  EPDfeed r3EPDeffic

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REV Efficiency

• What is the value (increased profit) from a
  unit change in efficiency, with no changes in the
  other traits in our objective (ie sale weight or
  feed costs)?

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REV Efficiency

• What is the value (increased profit) from a
  unit change in efficiency, with no changes in the
  other traits in our objective (ie sale weight or
  feed costs)?
• The answer is there is no change in profit

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Index Value

• INDEX r1EPDwt - r2EPDfeed r3EPDeffic
• INDEX (beef price) EPDwt (feed cost)
  EPDfeed
• We dont need an EPD for efficiency

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REV Efficiency

• Efficiency is therefore not an economically
  relevant trait (ERT) provided sale weight and
  feed intake are included in our objective
• Efficiency is not a line item in our financial
  statements
• Sale revenue and feed costs are line items
• Efficiency is however a useful fundamental or key
  performance indicator (KPI)

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Graphical Consideration of Issue
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Points form an ellipse Shape of ellipse
dependsupon genetic correlation
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O
Average Performance
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O
Average Performance 650 lb / 4000 lb 0.1625
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Feed Efficiency

• Efficiency typically measures output divided
  by input
• Big numbers are desirable
• Lbs gain per lbs feed (eg 1/6 0.16 lb/lb)
• Alternative is feed conversion rate
• input over output
• Small numbers are desirable
• Lbs feed per lb gain (eg 6 lb/lb)
• Rankings are equivalent

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O
488 lb / 3000 lb 0.1625
Average Performance 650 lb / 4000 lb 0.1625
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O
814 lb / 5000 lb 0.1625
488 lb / 3000 lb 0.1625
Average Performance 650 lb / 4000 lb 0.1625
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Iso-efficiency Line
O
814 lb / 5000 lb 0.1625
488 lb / 3000 lb 0.1625
Average Performance 650 lb / 4000 lb 0.1625
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Iso-efficiency

• All animals on the line have the same efficiency
• If efficiency was your goal, you would be equally
  happy with any of those animals

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O
Average Performance
Where do you want to move the average ?
30
O
Increased Sale weight Increases Revenue 0.86/lb
BWT 100/116 lb
Average Performance
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Decreased feed costs 5.70 per 100 lb DM 1750 lb
costs 100
O
Increased Sale weight Increases Revenue 0.86/lb
BWT 100/116 lb
Where do you want to move the average ?
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O
33
O
Iso-income line
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Most Profitable
Most Efficient
Least Efficient
Least Profitable
Do you want efficiency or profitability ?
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Summary so far

• We need good EPDs
• For outputs (Sale weight Value)
• For inputs (Feed intake, Health, Labor)
• Selection on overall value that rewards output
  and penalizes inputs will increase efficiency
• We dont need an efficiency (or conversion) EPD

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Determining Feed Intake

• Feed requirements are determined by
• Maintenance requirements
• Metabolic body weight, condition score, milk
  potential
• Activity Climate (if not thermo-neutral)
• Production
• Gain, pregnancy, lactation, (replacements)
• Unique (unknown) factors that differ from one
  animal to another (eg proton leak) (ie RFI)

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Predicting Feed Intake

• Could measure feed intake
• Easier in a feedlot than extensive grazing
• Subject to measurement other errors
• Could predict expected feed intake from knowledge
  of productivity
• Will account for most of the variation in feed
  requirements
• Will not account for variation in efficiency
  known as residual feed intake or RFI

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Index Value

• INDEX (beef price) EPDwt (feed cost)
  EPDfeed
• INDEX (beef price) EPDwt (feed cost)
  EPDpredicted feed (feed cost) EPDRFI

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Index Value

• If we dont have intake observations all animals
  will have the same EPD for RFI
• Cannot predict it from correlated characters, as
  if we could, we can come up with a better
  predicted feed
• RFI is the part of feed intake we cannot explain

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National Perspective

• With or without individual feed intake
• Predict feed intake from performance
• Dont need feed intake EPD per se
• Depends upon for eg rate of gain
• Account for the cost of predicted feed in
  decision support using performance ( repro) EPDs
• With individual feed intake
• Predict an EPD for residual feed intake
• Account for the cost/saving of RFI along with
  predicted feed in decision support

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Feed Intake Milestone

• Before we get individual feed intakes
• Use predicted requirements
• For cow-calf
• Need mature weights CS
• Need heifer pregnancy stayability
• Need Total Herd Recording (THR)
• After we get individual feed intakes
• Only change will be EPDs for RFI

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Getting Feed Intake

• No standards/guidelines for calculating feed
  intake
• Role for BIF
• No existing infrastructure for collecting feed
  intake
• Role for Breed Association

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Summary

• Selection for profit requires measures of outputs
  and inputs
• Dont need an EPD for efficiency or intake
• Predict inputs from knowledge of production
• Better estimates of cow-calf inputs require THR
• Immediate opportunity to improve existing
  cow-calf recording practices and more fully
  account for expected feed requirements
• Future opportunity to collect actual feed intake
  outcome will be RFI

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Alternative List of Traits

• Suppose our list of traits had only included
• Sale weight
• Feed Efficiency

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Economic Values

• What is the value of a unit change in sale weight
  with no change in feed efficiency?
• The answer is no longer the sale price

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Sale Wt Economic Values

• What is the value of a unit change in sale weight
  with no change in feed efficiency?
• The answer is no longer the sale price
• If sale weight increases, and efficiency of gain
  is unchanged, more feed will be required
• The answer is the sale price less the cost of the
  feed required for the extra gain
• But marginal and average efficiency may differ

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Feed Effic Economic Values

• What is the value of a unit change in feed
  efficiency with no change in sale weight?
• The answer is not straightforward it depends
  upon the feed cost and the amount of feed
  consumed
• We cant put a value on feed efficiency without
  considering feed intake