Fast-forward EPDs, accuracy values

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Adding DNA information to the American Angus Association® National Cattle Evaluation helps improve the dependability of expected progeny differences (EPD), which is reflected in increased accuracy values. But the question is, how much? And what’s this improvement worth? Kent Andersen, Ph.D., associate director, technical services, Pfizer Animal Genetics, says one way to better understand this technology and its impact is to express the change in EPD values and accuracies in terms of the equivalent number of progeny with performance records included in the genetic evaluation.

 “It’s hard to know exactly what a boost in accuracy of around .25 means for an EPD,” Dr. Andersen says. “But equating the enhanced accuracy for each trait to the equivalent number of progeny with performance records required for that level of improved accuracy helps put a complicated concept into more relatable terms for Angus breeders and buyers.”

 To better understand the number of progeny equivalents associated with genomic-enhanced EPDs (GE-EPDs) powered by High-Density 50K (HD 50K), EPDs were reviewed for almost 500 head, both before and after the addition of DNA information. Then, taking into account the heritability of each trait and the correlations computed by Angus Genetics, Inc.® (AGI) to enable GE-EPDs, the respective improvements in accuracy values were calculated and expressed in approximate progeny equivalents.

 The results, available in Table 1, show that depending on the trait, the average increase in accuracy for animals with initial EPDs based only on pedigree information, accuracy of .05, was equal to the addition of seven to 20 progeny performance records. For example, with HD 50K the GE-EPDs and accuracy values for weaning weight are equal to the addition of weaning weights in contemporary groups from approximately 16 progeny included in the genetic evaluation.

 “For females, these improvements in the dependability of EPDs equal more than a lifetime of progeny performance records, which enables years of more profitable mating decisions,” Dr. Andersen says. “And for bulls this increase in accuracy can equal a significant portion of a first calf crop ─ leading to less risky and more dependable selection decisions.”

 But the best news is that with GE-EPDs powered by HD 50K, this information is available on Angus cattle at a young age — prior to the availability of any progeny records, he says. And HD 50K comes with parentage verification at no additional charge when samples are processed through AGI.

 “Other than lots of progeny performance data, nothing delivers greater dependability across the full spectrum of traits than GE-EPDs powered by HD 50K,” Dr. Andersen says. “This is especially meaningful when it comes to predicting the genetic merit of young, unproven Angus cattle and enhancing the scope of selection for difficult, time-consuming and hard-to-measure traits.”

 

Table 1: GE-EPDs and Approximate Progeny Equivalents

 

AGI Heritability

AGI HD 50K Correlation

Average

Change in EPD

from HD 50K1

Avg. 50K Change in ACC  from .052

Approximate Progeny Equivalents

Birth Weight

0.42

0.51

±.45 lb.

0.25

8

Weaning Weight

0.20

0.52

±2.2 lbs.

0.23

16

Residual Average Daily Gain3

0.31

0.65

±.03 lbs./day

0.27

13

Yearling Weight4

0.20

0.64

±3.1 lbs.

0.27

20

Milking Ability

0.14

0.32

±1.2 lbs.

0.15

12

Carcass Weight

0.31

0.48

±4.1 lbs.

0.17

7

Fat Thickness5

0.26

0.56

±.01 in.

0.23

11

Ribeye Area5

0.32

0.60

±.10 in.2

0.23

9

Marbling Score5

0.26

0.57

±.08 units

0.24

12

1 Derived from Angus animals with ≤ .30 accuracy

2 Represents accuracy from only pedigree information

3 Dry matter intake

4 Post-weaning ADG

5 Carcass progeny records — equivalent to more than 30 scanned progeny records

All brands are the property of their respective owners. ©2011 Pfizer Inc. All rights reserved. PAG11037.


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kent    
MO  |  August, 24, 2011 at 05:03 PM

These tools are amazing and one that we should utilize. However depending on the trait, some marker tests are not highly correlated to the actual trait. For example I question the .65 correlation of the HD test for RADG. If it was only for dry matter intake (which it refers to in the foot notes) it may be. But how much value does knowing that an animal has the ability to eat a lot of feed have if we don't know what they do with it? Most of the research I have read shows a very low (sometime even negative) correlation between the markers and actual residual feed intake. It appears to me to be a good news bad news situation. The bad news is that the markers are not accurate for some traits. The good news is with time and more research someday they will be.


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