This document summarizes the genetic evaluation of stillbirth in US Holsteins using a sire-maternal grandsire threshold model. Over 6 million stillbirth records from 1980-2005 were analyzed. Heritability of direct and maternal stillbirth was estimated to be 3.0% and 6.5%, respectively. Genetic and phenotypic trends for stillbirth over time were small. Stillbirth EPDs were included in the US National Milk Progeny Test program starting in August 2006 and the US began participating in Interbull evaluations for calving traits in November 2006.

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J.B. Cole,* G.R. Wiggans, and P.M. VanRadenJ.B. Cole,* G.R. Wiggans, and P.M. VanRaden
Animal Improvement Programs Laboratory
Agricultural Research Service, USDA, Beltsville, MD
jcole@aipl.arsusda.gov
Genetic Evaluation of Stillbirth in USGenetic Evaluation of Stillbirth in US
Holsteins Using a Sire-maternalHolsteins Using a Sire-maternal
Grandsire Threshold ModelGrandsire Threshold Model

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IntroductionIntroduction
 Stillbirth is a genetically-controlled trait.
 Producers are concerned about stillbirth.
 Calf livability scores are already delivered
with calving ease data.
 Participation in Interbull evaluations for
both calving ease (CE) and stillbirth (SB)
is desirable.

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Stillbirth DefinitionStillbirth Definition
 Reported on a three-point scale:
 Scores of 2 and 3 are combined.
1 = calf born alive,
2 = calf born dead,
3 = calf died within 48 h of
parturition.

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Data and EditsData and Edits
 6 million SB records were available
for Holstein cows calving since 1980.
 Herds needed ≥10 calving records
with SB scores of 2 or 3 for inclusion.
 Herd-years were required to include
≥20 records.
 Only single births were used (no
twins).

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Stillbirth DataStillbirth Data
Alive Dead Died Usable
Parity 1 2 3 Records
1 88.6% 10.9% 0.5% 1,596,693
2+ 94.7% 4.8% 0.5% 4,448,187
Usable
Records 5,627,952 387,606 29,322 6,044,880
Stillbirth Score

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Genetic Evaluation ModelGenetic Evaluation Model
 A sire-maternal grandsire (MGS)
threshold model was used:
• Fixed: year-season, parity-sex, sire and
MGS birth year;
• Random: herd-year, sire, MGS.
 (Co)variance components were
estimated by Gibbs sampling.
• Heritabilities are 3.0% (direct) and 6.5%
(MGS).
ijklnoprnplonlkjiijklnopr emsBMBSPSYShyy +++++++= ijklnoprnplonlkjiijklnopr emsBMBSPSYShyy +++++++= ijklnoprnplonlkjiijklnopr emsBMBSPSYShyy +++++++=

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Trait DefinitionTrait Definition
 PTA are expressed as the expected
percentage of stillbirths.
 Direct SB measures the effect of the calf
itself.
 Maternal SB measures the effect of a
particular cow (daughter).
 A base of 8% was used for both traits:
 Direct: bulls born 1996–2000;
 Maternal: bulls born 1991–1995.

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Phenotypic Trend for StillbirthsPhenotypic Trend for Stillbirths
0
2
4
6
8
10
12
14
1980
1983
1986
1989
1992
1995
1998
2001
2004
Birth Year
%Stillbirth
Heifers
Cows
All animals

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Genetic Trend for StillbirthsGenetic Trend for Stillbirths
5.0
6.0
7.0
8.0
9.0
10.0
1980 1985 1990 1995 2000
Birth Year
%SBH
Direct
Maternal

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Distribution of PTADistribution of PTA
0
5
10
15
20
25
30
35
40 6.1-6.56.6-7.07.1-7.57.6-8.08.1-8.58.6-9.09.1-9.59.6-10.0
10.1-10.510.6-11.011.1-11.511.6-12.0
>12.0
%SBH
PercentofScores
Direct
Maternal

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Distribution of ReliabilitiesDistribution of Reliabilities
0
5
10
15
20
25
30
35
40
45
50 41-45
46-50
51-55
56-60
61-65
66-70
71-75
76-80
81-85
86-90
91-95
96-99
Reliability
Percentage
Direct
Maternal

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Dystocia and StillbirthDystocia and Stillbirth
 Meyer et al. (2001b) make a strong argument
for the inclusion of dystocia in models for SB.
 Difficulty of interpretation - formidable
educational challenge.
 Interbull trait harmonization - none of the
March 2006 test run participants included
dystocia in their models.
 Changes in sire and MGS solutions on the
underlying scale between models were small.

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Correlations among domestic andCorrelations among domestic and
Interbull SB solutionsInterbull SB solutions ((≥≥90% Rel on both scales)90% Rel on both scales)
Direct Maternal
Switzerland 0.90 0.85
Denmark 0.78 0.75
Finland 0.65 0.96
Netherlands 0.71 0.69
Sweden 0.63 0.89

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Genetic Correlations Among SB and CEGenetic Correlations Among SB and CE
Trait
CE SB
Direct Maternal Direct Maternal
CE
Direct 1.00 0.46 0.67 0.25
Maternal 1.00 0.29 0.63
SB
Direct 1.00 0.28
Maternal 1.00

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Calving Ability IndexCalving Ability Index
 CA$ has a genetic correlation of 0.85 with
the combined direct and maternal CE
values in 2003 NM$ and 0.77 with maternal
CE in TPI.
 Calving traits receive 6% of the total
emphasis in NM$ (August 2006 revision).
(DCE ) (MCE ) (DSB ) (MSCA$ B )= − − − − − − − −4 8 3 8 4 8 8 8

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ConclusionsConclusions
 Number of SB records (6 million) was
about half of calving ease records (14
million).
 Reliabilities for SB averaged 45%
versus 60% for CE.
 Phenotypic and genetic trends from
1980 to 2005 were both small.
 An industry-wide effort is underway to
improve recording of calf livability.

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ConclusionsConclusions
 A routine evaluation for stillbirth in US
Holsteins was implemented in August 2006.
 Direct and maternal stillbirth were included in
NM$ for Holsteins starting in August 2006.
 August 2006 data were sent to Interbull for
the September 2006 test run for calving traits.
 The US will participate in routine Interbull
evaluations beginning in November 2006.

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AcknowledgmentsAcknowledgments
 Jeff Berger, Iowa State University
 John Clay, Dairy Records Management
Systems
 Ignacy Misztal and Shogo Tsuruta,
University of Georgia