how do i decide what traits are important? carcass/ultrasound epds

1Brown Bagger – Beef Cattle Genetics:

Fine Tuning Selection Decisions

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

Bob WeaberGRA-Cornell Univ. Animal Breeding Group

[email protected]

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

OverviewWhich trait should be used in making

selection decisions? Ultrasound or Carcass

The value of ultrasound recordsOverview of various breed

carcass/ultrasound genetic evaluations


Alternate Production Circumstance

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


Example Feedlot Goal

Maximize the income from beef (carcass) less the production costs Production costs include weanling

purchase price and per diem feeding costs


Example List of Traits

Carcass attributes (eg carcass marbling)

Ultrasound attributes (eg ultrasound marbling)

Days to finish


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 ?


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


The value of ultrasound records


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


Genetic correlations

Ultrasound Trait

σp h2 Correlated Carcass Trait

rg

Live Wt 82.3 0.47 HCW 0.77

Bull FAT 0.055 0.53 FAT 0.79

Bull REA 1.17 0.37 REA 0.80

Bull IMF 0.522 0.47 MARB 0.74SE (h2) < 0.07, SE (Rg) < 0.13

Crews et al. 2003a


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


Relationships

Observed Carcass Data

Observed Ultrasound Data

True Carcass Attribute True Carcass Attribute

Progeny

Carcass

Attributes

Enns, 2003

Ultrasound EPD

Carcass EPD


OptionsEPD calculated using carcass dataEPD calculated using ultrasound dataCarcass EPD calculated using carcass

and ultrasound data

Ultrasound data is useful Indicator trait


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)


Current Carcass/Ultrasound Genetic Evaluations


Current Genetic Evaluations

Breed Carconly

Ultraonly

C-UMT

Traits Reported Traits Not Reported

Angus CWT, MARB, REA, FT, %RP%IMF, UREA, UFT, URFT, U%RP

Brangus UREA, UFT, %IMF

Charolais CWT, MARB, REA, FT

Gelbvieh CWT, MARB, REA, FT

Hereford * UREA, UFT, %IMF

Limousin CWT, MARB, REA, FT%IMF, UREA, UFT

*Working to incorporate carcass data, Spring 2004 release


Current Genetic Evaluations

Breed Carconly

Ultraonly

C-UMT

Traits Reported Traits Not Reported

Maine-Anjou * CWT, %RP, MARB, FT, REA

SCWT, %IMF, UFT, UREA

Red Angus REA, MARB, FT

%IMF, UREA

Salers * CWT, MARB, REA, FT, %RP


Shorthorn * CWT, MARB, REA, FT, %RP


Simmental * CWT, %RP, MARB, FT, REA


*Multi-breed model


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


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.

how do i decide what traits are important? carcass/ultrasound epds

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