Breed and Trait Selection Considerations Dan W. Moser Dept. of Animal Sciences and Industry Kansas State University

Outline Breed Selection Considerations Breed Selection Considerations  General  Seedstock-Specific Trait Selection Considerations Trait Selection Considerations  General  Commercial-Specific  Seedstock-Specific

Breed Selection Considerations Genetic Merit / Breeding Value Genetic Merit / Breeding Value Breed Complimentarity Breed Complimentarity Specific Heterosis (Combining Ability) Specific Heterosis (Combining Ability) Uniformity of Offspring Uniformity of Offspring Maternal/Terminal Roles Maternal/Terminal Roles Breed Direction Breed Direction

Breed Selection Considerations Genetic Antagonisms Genetic Antagonisms Genetic Evaluation Genetic Evaluation Other Breed-Specific Services Other Breed-Specific Services Market Realities and Perceptions Market Realities and Perceptions Dynamic Nature of the Industry Dynamic Nature of the Industry External Factors External Factors

Genetic Merit of Breeds Van Vleck and Cundiff, 2003

Genetic Merit of Breeds Breeds differ for: Breeds differ for:  Maintenance  Reproduction  Carcass Genetic merit must match production environment. Genetic merit must match production environment. Some economically relevant traits go unmeasured. Some economically relevant traits go unmeasured.

Unmeasured/Unreported Traits Mature cow size Mature cow size Reproductive data Reproductive data Feed intake Feed intake Shear force Shear force

Specific Heterosis A “Lost Science”? A “Lost Science”? Not all heterosis is created equally Not all heterosis is created equally Depends on the genetic similarity of the breeds being crossed Depends on the genetic similarity of the breeds being crossed Just as traits vary in heritability, traits also vary in effects of heterosis Just as traits vary in heritability, traits also vary in effects of heterosis

Specific Heterosis Survival to Weaning, Direct, % ANCHGVHHLM CH2.01 GV HH LM SM Roughsedge et al., 2001

Specific Heterosis Post Weaning Gain, % ANCHGVHHLM CH4.64 GV HH LM SM Roughsedge et al., 2001

Specific Heterosis Cow Fertility, % ANCHGVHHLM CH7.74 GV HH LM SM Roughsedge et al., 2001

Breed Complimentarity Combine breeds to overcome antagonisms Combine breeds to overcome antagonisms Not the best of both, but the average of both, plus heterosis Not the best of both, but the average of both, plus heterosis

Breed Complimentarity Van Vleck and Cundiff, 2003

Breed Complimentarity Rotational crossing using purebred sires that differ in biological type: Rotational crossing using purebred sires that differ in biological type:  benefits from complimentarity  reduces uniformity (across the calf crop)

Breed Complimentarity Crossing purebred sires of different breeds but similar biological type: Crossing purebred sires of different breeds but similar biological type:  improves uniformity  reduces complimentarity  may reduce effects of heterosis

Breed Complimentarity Hybrids and composites have the ability to offer both complimentarity and uniformity Hybrids and composites have the ability to offer both complimentarity and uniformity  Only a slight reduction in heterosis compared to using purebred sires  All calves are same breed composition  Also simplifies execution of the crossbreeding system

Breed Selection: Seedstock Rarely do seedstock operators completely change breeds. Rarely do seedstock operators completely change breeds. Opportunities exist to: Opportunities exist to:  Add breeds  Add F 1 ’s  Add composites

Evolution of Seedstock Production Purebred, Single Breed Purebred, Multi-Breed Purebred (Multi-Breed) and F 1 Purebred (Multi- Breed), F 1, and Composite

Weaning Weight Genetic Trend

Maternal Milk Genetic Trend

Trait Selection Considerations Economic Importance Economic Importance Heritability and Heterosis Heritability and Heterosis Method of Multiple Trait Selection Method of Multiple Trait Selection Genetic Antagonisms Genetic Antagonisms Maternal/Terminal Roles Maternal/Terminal Roles Market Realities and Perceptions Market Realities and Perceptions Dynamic Nature of the Industry Dynamic Nature of the Industry

Heritability Portion of a trait’s variation attributable to additive genetics Portion of a trait’s variation attributable to additive genetics In general, heritability is: In general, heritability is:  High for carcass traits and mature size  Moderate for growth rate and milk production  Low for reproductive traits

Heritability Highly heritable traits are the easiest to change with selection Highly heritable traits are the easiest to change with selection Traits that are low in heritability can be changed with selection, but change is slower Traits that are low in heritability can be changed with selection, but change is slower Heritability of a trait is reflected in the range of EPD across a population Heritability of a trait is reflected in the range of EPD across a population

Heterosis Trait %HV I %HV M %HV P Birth Weight Weaning Weight Calves weaned/cow exp Lbs. weaned/cow exp Feed Conversion (F/G) -- Age at Puberty Bourdon, 2000

Heritability vs. Heterosis Logical for commercial producers to: Logical for commercial producers to:  Select mainly for moderate and highly heritable traits  Depend on heterosis to ensure adequate levels of traits low in heritability Seedstock producers cannot ignore traits that are low in heritability Seedstock producers cannot ignore traits that are low in heritability

Methods of Multiple-Trait Selection Independent Culling Levels Independent Culling Levels  Most commonly used  Set min/max levels for each trait (EPD) Selection Index Selection Index  Most effective for overcoming antagonisms  Weight traits (EPD) on economic importance

Independent Culling Levels Possible to “just miss” some bulls that offer superior genetic combinations Possible to “just miss” some bulls that offer superior genetic combinations Limit the ability to overcome antagonisms Limit the ability to overcome antagonisms

Selection Index Fairly straightforward for terminal sires Fairly straightforward for terminal sires Much more complex for maternal lines Much more complex for maternal lines Currently applied in other species, and for beef on other continents Currently applied in other species, and for beef on other continents

Selection Index Selection Index is fairly robust. Selection Index is fairly robust. Need the ability to enter index weights into sire sort web pages… Need the ability to enter index weights into sire sort web pages…  Or at least download sire summaries in a spreadsheet format. Precise economic weights are under development, are we ready to apply them? Precise economic weights are under development, are we ready to apply them?