2004 r.l. powell,* a.h. sanders, and h.d. norman animal improvement programs laboratory agricultural...
TRANSCRIPT
2004
2004
2004
R.L. Powell,* A.H. Sanders, and H.D. NormanAnimal Improvement Programs LaboratoryAgricultural Research Service, USDA, Beltsville, [email protected]
Accuracy and stability of national and international
somatic cell score evaluations
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Objectives
Investigate the accuracy and stability of somatic cell score evaluations
From US data (study one) • Overall• By bull sampling status
‘S’ Standard sampling, defined by NAAB‘O’ Other (alternative) sampling
From Interbull data (study two)• For bulls with US evaluations• By inclusion of foreign daughters
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DataStudy One
20,811 Holstein bulls born in 1985 or later
17,992 Sampling status ‘S’2819 Sampling status ‘O’
481,416 US SCS evaluations from 1995 through February 2004 compared to May 2004 evaluations
6,975,946 pairs of evaluations including all evaluation pairs for each bull
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MethodsStudy One
Mean change, absolute change, SD and expected SD of change where:
Between each evaluation and the May 2004 evaluation, for all bulls and by sampling status
Within all pairs of evaluations, by change in reliability (REL)
E(SD) = SDsireREL
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ResultsStudy One
Overall, May 2004 PTA SCS were greater than earlier evaluations
SD of change in evaluations were larger than E(SD)
For evaluations prior to 2000, SD of change averaged 19% larger than E(SD)
For later evaluations, SD of change was 10% larger than E(SD)
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ResultsStudy One
SD of change exceeded E(SD) more with smaller increases in REL
For changes in REL less than .05, SD of change was 25% greater than E(SD)
For changes in REL from .10 to .30, SD of change was 8% greater than E(SD)
Sampling status can affect accuracy‘O’ bull first evaluations changed less
but increased less in REL‘S’ bull evaluations with an opportunity
for 2nd crop daughters more accurate
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DataStudy Two
13,624 Holstein bulls with only US daughters in Interbull evaluations for May 2001
1028 Holstein bulls with US and additional foreign daughters included in Interbull evaluations
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MethodsStudy Two
Correlations of 2001 with 2004 evaluations and regressions of 2004 on 2001 evaluations
By increase in US daughters from 2001 to 2004
For bulls with Interbull evaluations including:
• US daughters only (US-only)• US and foreign daughters (Multi-
country)
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ResultsStudy Two
Number of bulls
Correlation ofIB01 with IB04
US01 with US04
IB01 with US04
US-only bulls 13,624 0.960 0.963 0.962 >25% daus1 1715 0.849 0.854 0.854 >50% daus1 1211 0.835 0.841 0.841 >100% daus1 855 0.829 0.835 0.836 >200% daus1 569 0.808 0.813 0.814
Multi-country bulls 1028 0.972 0.970 0.929 >25% daus1 195 0.936 0.909 0.912 >50% daus1 149 0.926 0.889 0.905 >100% daus1 102 0.900 0.850 0.874
1Percent increase in US daughters from May 2001 to May 2004.
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ResultsStudy Two
Number of bulls
Correlation ofIB01 with IB04
US01 with US04
IB01 with US04
US-only bulls 13,624 0.960 0.963 0.962 >25% daus1 1715 0.849 0.854 0.854 >50% daus1 1211 0.835 0.841 0.841 >100% daus1 855 0.829 0.835 0.836 >200% daus1 569 0.808 0.813 0.814
Multi-country bulls 1028 0.972 0.970 0.929 >25% daus1 195 0.936 0.909 0.912 >50% daus1 149 0.926 0.889 0.905 >100% daus1 102 0.900 0.850 0.874
1Percent increase in US daughters from May 2001 to May 2004.
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ResultsStudy Two
Number of
bulls
Regression ofIB04 on IB01
US04 on
US01
US04 on IB01 SE
US-only bulls13,62
4 0.99 0.99 0.99 0.002
>25% daus1 1715 1.01 1.00 1.010.01-0.02
>50% daus1 1211 1.00 1.00 1.00 0.01 >100% daus1 855 1.00 1.01 1.01 0.02 >200% daus1 569 0.99 1.00 1.00 0.03
Multi-country bulls
1028 0.98 0.98 0.89 0.01
>25% daus1 195 0.99 0.97 0.96 0.03
>50% daus1 149 0.98 0.95 0.940.03-0.04
>100% daus1 102 0.97 0.95 0.930.06-0.08
1Percent increase in US daughters from May 2001 to May 2004.
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Conclusions
Mean PTA SCS tended to increase slightly over time and as REL increased
Addition of daughters caused greater than expected changes in PTA SCS
Correlations and regressions of US and Interbull 2001 and 2004 evaluations were near expectations
Foreign data improved prediction of later US PTA