how do i decide what traits are important ? selection indices

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1 Brown Bagger – Beef Cattle Genetics: Fine Tuning Selection Decisions How do I decide what traits are important ? Selection Indices Dorian Garrick Department of Animal Sciences Colorado State University

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How do I decide what traits are important ? Selection Indices. Dorian Garrick Department of Animal Sciences Colorado State University. How do I decide ?. Not by looking at bulls and sire summaries. I decide what is important . By first looking at myself, my environment and my business - PowerPoint PPT Presentation

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Page 1: How do I decide  what traits are important ? Selection Indices

1Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions

How do I decide what traits are important ?

Selection Indices

Dorian GarrickDepartment of Animal SciencesColorado State University

Page 2: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 2

How do I decide ?

Not by looking at bulls and sire summaries

Page 3: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 3

I decide what is important

By first looking at myself, my environment and my business and considering likely future trends

Page 4: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 4

Systematic Approach

Breeding ObjectiveSelection Criteria

DisseminationSystem

Economic Analysis

Goal

Breeding SchemeDesign

Mating Plan

Page 5: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 5

Systematic Approach

Breeding ObjectiveSelection Criteria

DisseminationSystem

Economic Analysis

Goal

Breeding SchemeDesign

Mating Plan

Page 6: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 6

Who are you?Bull breeder

Actively involved in pedigree & performance recording

Have control over the nature & extent of performance recording on your animals

Bull buyer Primarily interested in deciding which of the

bulls on offer will give the greatest advance

Page 7: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 7

Systematic Approach

Breeding ObjectiveSelection Criteria

DisseminationSystem

Economic Analysis

Goal

Breeding SchemeDesign

Mating Plan

The purposeof change

Page 8: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 8

GoalThe purpose to which an endeavor is

directedWe always want to increase utility

(economic speak for satisfaction)Most producers would be more satisfied

if they could increase the profit of their ranch business

Page 9: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 9

GoalProfit is usually an important component

of a business Not the only component Lifestyle, family values and environmental

considerations are often an important part If profit is not a component, we are

probably dealing with a hobby rather than a business

Page 10: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 10

Systematic Approach

Breeding ObjectiveSelection Criteria

DisseminationSystem

Economic Analysis

Goal

Breeding SchemeDesign

Mating Plan

What to change& the value of change

Page 11: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 11

Breeding ObjectiveSometimes called selection objective Involves two components

A list of traits that influence the goal Relative emphasis of each trait in the list

These quantify the extent to which you will compromise superiority in one trait for inferiority in another

Relative emphasis for a profit-based goals can be measured using relative economic values (REVs)

Page 12: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 12

Breeding Objective

It is this list of traits that comprise the breeding objective that establishes the list of EPDs that should be of primary interest

Page 13: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 13

Systematic Approach

Breeding ObjectiveSelection Criteria

DisseminationSystem

Economic Analysis

Goal

Breeding SchemeDesign

Mating Plan

What tomeasure

Page 14: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 14

Selection Criteria These are the animal characteristics that are

physically recorded on individual animals in order to generate EPDs for each of the traits in the breeding objective Some of these characteristics might be the actual trait

of interest (eg sale weight) Others may be indicator traits that are used to improve

the prediction of EPDs in the breeding objective (eg scrotal circumference for female fertility)

We don’t need EPDs for selection criteria per se

Page 15: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 15

Systematic Approach

Breeding ObjectiveSelection Criteria

DisseminationSystem

Economic Analysis

Goal

Breeding SchemeDesign

Mating Plan

Is this worthwhile

Page 16: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 16

Economic AnalysisConsideration of the response to selection in

relation to cost and effortBull breeders perspective

Does the effort of collecting additional selection criteria lead to significantly improved response relative to my goal

Bull buyers perspective Does the benefit of using a more desirable

bull/straw outweigh the purchase premium relative to an average bull

Page 17: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 17

Production Circumstance

Cow-calf operation grazing rangeland and selling weanling cattle

Page 18: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 18

Example Cow-Calf Goal

Maximize the total weight of sale weanling cattle crossing the cattle guard each year Total weight = number sold

x average weight

Page 19: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 19

Example List of Traits

Birth Weight Calving Ease Sale (weaning) Weight

Direct and maternal components Cow Maintenance Feed Stayability Heifer Pregnancy

Page 20: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 20

See last years Brownbagger for consideration of the value of weaning weight (adjusting for cow maintenance increases) and stayability

Page 21: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 21

Example List of Traits

Birth Weight Calving Ease Sale (weaning) Weight

Direct and maternal components Cow Maintenance Feed Stayability Heifer Pregnancy

Page 22: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 22

Relative Emphasis of Birth Weight & Calving Ease

What is the change in profit of a unit change in birth weight with other traits in the list held constant ? No change in sale weight or calving ease

What is the change in profit of a unit change in calving ease with no change in birth weight ?

Page 23: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 23

The Answer Birth weight has no value in itself (it is simply an

indicator trait) when both calving ease and sale weight are included in the breeding objective Assuming birth weight is used as a correlated trait in

multiple trait evaluations of calving ease and multiple trait evaluations of sale weight

The value of calving ease is influenced by its impact on the number of sale calves, veterinary costs (for the cow) and the cows subsequent performance

Page 24: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 24

Example Selection Index Includes EPDs only for those traits that

are economically relevant Those that have nonzero economic values

Does not exclude information from any useful selection criteria Makes use of phenotypic data on indicator

traits to improve the accuracy of EPDs for correlated economically relevant traits

Achieved through multiple trait evaluation

Page 25: How do I decide  what traits are important ? Selection Indices

Brown Bagger – Beef Cattle Genetics:Fine Tuning Selection Decisions 25

Summary We can select on a measure of aggregate

merit that directly relates to our business goal By identifying the list of traits that influence our

goal (EPD1, EPD2, EPD3) By quantifying the relative emphasis appropriate

for each trait in the list (r1, r2, r3) By constructing the index values

$index=r1EPD1 + r2EPD2 + r3EPD3