Breed and Trait Selection Considerations

Dan W. MoserDan W. Moser

Dept. of Animal Sciences and Dept. of Animal Sciences and IndustryIndustry

Kansas State UniversityKansas State University

Outline

Breed Selection ConsiderationsBreed Selection Considerations GeneralGeneral Seedstock-SpecificSeedstock-Specific

Trait Selection ConsiderationsTrait Selection Considerations GeneralGeneral Commercial-SpecificCommercial-Specific Seedstock-SpecificSeedstock-Specific

Breed Selection Considerations

Genetic Merit / Breeding ValueGenetic Merit / Breeding Value Breed ComplimentarityBreed Complimentarity Specific Heterosis (Combining Specific Heterosis (Combining

Ability)Ability) Uniformity of OffspringUniformity of Offspring Maternal/Terminal RolesMaternal/Terminal Roles Breed DirectionBreed Direction

Breed Selection Considerations

Genetic AntagonismsGenetic Antagonisms Genetic EvaluationGenetic Evaluation Other Breed-Specific ServicesOther Breed-Specific Services Market Realities and PerceptionsMarket Realities and Perceptions Dynamic Nature of the IndustryDynamic Nature of the Industry External FactorsExternal Factors

Genetic Merit of Breeds

WW

Breed Average Across-Breed EPD

AngusBeefmasterBrangusCharolaisGelbviehHerefordLimousinRed AngusSimmental

Van Vleck and Cundiff, 2003

Genetic Merit of Breeds

Breeds differ for:Breeds differ for: MaintenanceMaintenance ReproductionReproduction CarcassCarcass

Genetic merit must match Genetic merit must match production environment.production environment.

Some economically relevant traits Some economically relevant traits go unmeasured.go unmeasured.

Unmeasured/Unreported Traits

Mature cow sizeMature cow size Reproductive dataReproductive data Feed intakeFeed intake Shear forceShear force

Specific Heterosis

A “Lost Science”?A “Lost Science”? Not all heterosis is created equallyNot all heterosis is created equally Depends on the genetic similarity Depends on the genetic similarity

of the breeds being crossedof the breeds being crossed Just as traits vary in heritability, Just as traits vary in heritability,

traits also vary in effects of traits also vary in effects of heterosisheterosis

Specific HeterosisSurvival to Weaning, Direct, %

ANAN CHCH GVGV HHHH LM LM

CHCH 2.012.01

GVGV 2.142.14 1.691.69

HHHH 2.522.52 2.772.77 3.493.49

LMLM 1.881.88 0.890.89 2.012.01 3.253.25

SMSM 1.281.28 1.051.05 1.121.12 2.822.82 1.281.28

Roughsedge et al., 2001

Specific HeterosisPost Weaning Gain, %

ANAN CHCH GVGV HHHH LM LM

CHCH 4.644.64

GVGV 4.944.94 3.913.91

HHHH 5.825.82 6.406.40 8.088.08

LMLM 4.354.35 2.062.06 4.644.64 7.517.51

SMSM 2.962.96 2.422.42 2.602.60 6.516.51 2.962.96

Roughsedge et al., 2001

Specific HeterosisCow Fertility, %

ANAN CHCH GVGV HHHH LM LM

CHCH 7.747.74

GVGV 8.248.24 6.526.52

HHHH 9.709.70 10.6810.68 13.4713.47

LMLM 7.257.25 3.443.44 7.747.74 12.5212.52

SMSM 4.944.94 4.034.03 4.334.33 10.8610.86 4.944.94

Roughsedge et al., 2001

Breed Complimentarity

Combine breeds to overcome Combine breeds to overcome antagonismsantagonisms

Not the Not the bestbest of both, but the of both, but the averageaverage of both, plus heterosis of both, plus heterosis

Breed Complimentarity

WW MILK

Breed Average Across-Breed EPD

AngusCharolaisGelbviehHerefordLimousinRed AngusSimmental

Van Vleck and Cundiff, 2003

Breed Complimentarity

Rotational crossing using Rotational crossing using purebred sires that differ in purebred sires that differ in biological type:biological type: benefits from complimentaritybenefits from complimentarity reduces uniformity (across the reduces uniformity (across the

calf crop)calf crop)

Breed Complimentarity

Crossing purebred sires of Crossing purebred sires of different breeds but similar different breeds but similar biological type:biological type: improves uniformityimproves uniformity reduces complimentarityreduces complimentarity may reduce effects of heterosismay reduce effects of heterosis

Breed Complimentarity

Hybrids and composites have the ability Hybrids and composites have the ability to offer both complimentarity and to offer both complimentarity and uniformityuniformity Only a slight reduction in heterosis Only a slight reduction in heterosis

compared to using purebred sirescompared to using purebred sires All calves are same breed compositionAll calves are same breed composition Also simplifies execution of the Also simplifies execution of the

crossbreeding systemcrossbreeding system

Breed Selection: Seedstock

Rarely do seedstock operators Rarely do seedstock operators completely change breeds.completely change breeds.

Opportunities exist to:Opportunities exist to: Add breedsAdd breeds Add FAdd F11’s’s Add compositesAdd composites

Evolution of Seedstock ProductionPurebred, Single Breed

Purebred, Multi-Breed

Purebred (Multi-Breed) and F1

Purebred (Multi-Breed), F1, and

Composite

Weaning WeightGenetic Trend

0

5

10

15

20

25

30

35

80 85 90 95 00

Calf Year of Birth

EP

D (

Po

un

ds

)

HerefordAngusSimmentalCharolais

Maternal MilkGenetic Trend

-2

0

24

6

8

10

1214

16

18

80 85 90 95 00

Calf Year of Birth

EP

D (

Po

un

ds

)

HerefordAngusSimmentalCharolais

Trait Selection Considerations

Economic ImportanceEconomic Importance Heritability and HeterosisHeritability and Heterosis Method of Multiple Trait SelectionMethod of Multiple Trait Selection Genetic AntagonismsGenetic Antagonisms Maternal/Terminal RolesMaternal/Terminal Roles Market Realities and PerceptionsMarket Realities and Perceptions Dynamic Nature of the IndustryDynamic Nature of the Industry

Heritability

Portion of a trait’s variation Portion of a trait’s variation attributable to additive geneticsattributable to additive genetics

In general, heritability is:In general, heritability is: High for carcass traits and High for carcass traits and

mature sizemature size Moderate for growth rate and Moderate for growth rate and

milk productionmilk production Low for reproductive traitsLow for reproductive traits

Heritability

Highly heritable traits are the Highly heritable traits are the easiest to change with selectioneasiest to change with selection

Traits that are low in heritability can Traits that are low in heritability can be changed with selection, but be changed with selection, but change is slower change is slower

Heritability of a trait is reflected in Heritability of a trait is reflected in the range of EPD across a populationthe range of EPD across a population

Heterosis

TraitTrait %HV%HVII %HV%HVMM %HV%HVPP

Birth WeightBirth Weight 3.03.0 1.51.5 --

Weaning WeightWeaning Weight 5.05.0 8.08.0 --

Calves weaned/cow Calves weaned/cow exp.exp.

3.03.0 8.08.0 5.05.0

Lbs. weaned/cow Lbs. weaned/cow exp.exp.

7.07.0 15.015.0 6.06.0

Feed Conversion Feed Conversion (F/G)(F/G)

-1.0-1.0 -- --

Age at PubertyAge at Puberty -5.5-5.5 -- --

Bourdon, 2000

Heritability vs. Heterosis

Logical for commercial producers to:Logical for commercial producers to: Select mainly for moderate and Select mainly for moderate and

highly heritable traitshighly heritable traits Depend on heterosis to ensure Depend on heterosis to ensure

adequate levels of traits low in adequate levels of traits low in heritabilityheritability

Seedstock producers cannot ignore Seedstock producers cannot ignore traits that are low in heritabilitytraits that are low in heritability

Methods ofMultiple-Trait Selection Independent Culling LevelsIndependent Culling Levels

Most commonly usedMost commonly used Set min/max levels for each trait Set min/max levels for each trait

(EPD)(EPD) Selection IndexSelection Index

Most effective for overcoming Most effective for overcoming antagonismsantagonisms

Weight traits (EPD) on economic Weight traits (EPD) on economic importanceimportance

Independent Culling Levels

Possible to “just miss” some bulls Possible to “just miss” some bulls that offer superior genetic that offer superior genetic combinationscombinations

Limit the ability to overcome Limit the ability to overcome antagonismsantagonisms

Selection Index

Fairly straightforward for terminal Fairly straightforward for terminal siressires

Much more complex for maternal Much more complex for maternal lineslines

Currently applied in other species, Currently applied in other species, and for beef on other continentsand for beef on other continents

Selection Index

Selection Index is fairly robust.Selection Index is fairly robust. Need the ability to enter index weights Need the ability to enter index weights

into sire sort web pages…into sire sort web pages… Or at least download sire summaries Or at least download sire summaries

in a spreadsheet format.in a spreadsheet format. Precise economic weights are under Precise economic weights are under

development, are we ready to apply development, are we ready to apply them?them?