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How Do I Decide What Traits are Important? Carcass/Ultrasound EPDs . Bob Weaber GRA-Cornell Univ. Animal Breeding Group [email protected] Overview. Which trait should be used in making selection decisions? Ultrasound or Carcass The value of ultrasound records

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How do i decide what traits are important carcass ultrasound epds l.jpg

How Do I Decide What Traits are Important? Carcass/Ultrasound EPDs

Bob Weaber

GRA-Cornell Univ. Animal Breeding Group

[email protected]


Overview l.jpg
Overview

  • Which trait should be used in making selection decisions?

    • Ultrasound or Carcass

  • The value of ultrasound records

  • Overview of various breed carcass/ultrasound genetic evaluations

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Alternate Production Circumstance

  • Feedlot owner buying bulls for the production of forward contract weanling cattle

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Example Feedlot Goal

  • Maximize the income from beef (carcass) less the production costs

    • Production costs include weanling purchase price and per diem feeding costs

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Example List of Traits

  • Carcass attributes (eg carcass marbling)

  • Ultrasound attributes (eg ultrasound marbling)

  • Days to finish

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Example Relative Emphasis

  • What is the increase in carcass value from a unit change in marbling score, all other traits (in the list) held constant ?

  • What is the increase in carcass value from a unit change in ultrasound score, all other traits (such as carcass marbling) held constant ?

  • What is the increase in costs from an extra day on feed ?

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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The Answer

  • Ultrasound attributes have no value in themselves when the income is determined by the corresponding carcass attribute and the ultrasound phenotypic measures have been used in the multiple trait assessment of carcass attributes

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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The value of ultrasound records

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Genetic Correlations

  • Carcass traits

    • Economically relevant

    • Observed in fed steer and heifer carcasses

  • Ultrasound

    • Indicator

    • Observed on yearling breeding stock

  • Genetic correlation links them

    • Want genetic predictors for carcass trait

    • Have (most) phenotypes on indicator trait

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Genetic correlations

SE (h2) < 0.07, SE (Rg) < 0.13

Crews et al. 2003a

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Why should we use ultrasound data?

  • Strong, positive genetic correlations

    • Suggests a high proportion of the same genes affect both traits

  • High heritabilities

    • Opportunity for rapid genetic change

  • Phenotypic record collection cost

    • Carcass ~ $100 vs. Ultrasound ~ $15

  • New records (2003):

    • Angus: 4,290 carcass, 88,167 ultrasound

    • Simmental: 724 carcass, 4,426 ultrasound

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


Relationships l.jpg

Observed Carcass Data

Carcass EPD

Observed Ultrasound Data

Ultrasound EPD

Relationships

Progeny

Carcass

Attributes

True Carcass Attribute

Enns, 2003

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Options

  • EPD calculated using carcass data

  • EPD calculated using ultrasound data

  • Carcass EPD calculated using carcass and ultrasound data

  • Ultrasound data is useful

    • Indicator trait

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Does it work?

  • Devitt and Wilton (2001) suggested the use of yearling bull ultrasound measures for genetic improvement of steer progeny carcass traits.

  • Selection of high- and low-line IMF phenotype sires randomly mated resulted in significant differences in progeny USDA QG. (Sapp et al. 2002)

  • Inclusion of ultrasound data in multiple trait evaluation improves accuracy of carcass EPD, especially for replacements with only an ultrasound observation. (Crews and Kemp, 2002; Crews et al., 2003b)

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Current Carcass/Ultrasound Genetic Evaluations

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Current Genetic Evaluations

*Working to incorporate carcass data, Spring 2004 release

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Current Genetic Evaluations

*Multi-breed model

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Which EPDs do I use?

  • Angus

    • Older animals-

      • Compare accuracy values from each evaluation

        • If very different use EPDs with highest accuracy

        • If similar use Carcass EPD given similar percentile rank as Ultrasound EPD

        • Else, use Ultrasound EPD

    • Young animals with own ultrasound observation or those with low carcass EPD accuracies

      • Ultrasound EPDs

  • Other breeds

    • Use reported EPDs

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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Selected References

  • Crews, D. H., Jr. and R. A. Kemp. 2002. Genetic evaluation of carcass yield using ultrasound measures on young replacement beef cattle. J. Anim. Sci. 80:1809-1818.

  • Crews, D. H., Jr., E. J. Pollak, R. L. Weaber, R. L. Quaas, and R. J. Lipsey. 2003. Genetic parameters for carcass traits and their live animal indicators in Simmental cattle. J. Anim. Sci. 81:1427-1433. 242

  • Crews, D. H., Jr., E. J. Pollak, R. L. Quaas. 2003. Evaluation of Simmental carcass EPD estimated using live and carcass data. Submitted J. Anim. Sci.

  • Devitt, C. J. B, and J. W. Wilton. 2001. Genetic correlation estimates between ultrasound measurements on yearling bulls and carcass measurements on finished steers. J. Anim. Sci. 79:2790-2797.

  • Sapp, R. L., J.K. Bertrand, T. D. Pringle, and D. E. Wilson. 2002. Effects of selection for ultrasound intramuscular fat percentage in Angus bulls on carcass traits of progeny. J. Anim. Sci. 80:2017-2022.

  • Wilson, D. E. 1992. Application of ultrasound for genetic improvement. J. Anim. Sci. 70:973-983.

Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions


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