6.1 Pests of Groundnut_Binomics_Identification_Dr.UPR
Genetic Evaluation of Calving Traits in US Holsteins
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J.B. ColeJ.B. Cole
Animal Improvement Programs Laboratory
Agricultural Research Service, USDA, Beltsville, MD
john.cole@ars.usda.gov
Genetic Evaluation of CalvingGenetic Evaluation of Calving
Traits in US HolsteinsTraits in US Holsteins
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IntroductionIntroduction
National evaluations were introduced for
Holstein calving ease (CE) in August 2002
and for stillbirth (SB) in August 2006.
A calving ability index (CA$) which
includes SB and calving ease (CE) was
developed.
Relationships among calving traits and
other diseases are being studied.
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Why the concern?Why the concern?
Calving difficulty and stillbirth are
expensive (Dematawewa and Berger,
1997; Meyer et al., 2001)
There is concern that rates of dystocia
and stillbirth are increasing
Lactations initiated with dystocia have
higher risks for other diseases (Cole et
al., unpublished data).
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How do the evaluations work?How do the evaluations work?
Funded by the National Association
of Animal Breeders
Data are collected from multiple
sources:
• Pedigree from breed associations
• Calving data from DRPC
Evaluated using a sire-maternal
grandsire threshold model
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Calving ease definitionCalving ease definition
Reported on a five-point scale:
1 = No problem
2 = Slight problem
3 = Needed assistance
4 = Considerable force
5 = Extreme difficulty
Scores of 4 and 5 are combined
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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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Distribution of SB and CE ScoresDistribution of SB and CE Scores
7,484,30929,320348,6775,348,0291,758,283Total
96,0871,27232,19638,92923,6905
207,2421,74037,851108,03759,6144
633,0293,35370,522375,203183,9513
738,8532,53749,858482,720203,7382
5,809,09820,418158,2504,343,1401,287,2901
Total3210
CalvingEaseScore
Stillbirth Score
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Stillbirth records by lactationStillbirth records by lactation
0
100
200
300
400
500
1980 1990 2000
Birth Year
NumberofRecords(thousands)
3
2
1
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Data and editsData and edits
7 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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Sire-MGS threshold modelSire-MGS threshold model
Implemented for calving ease (Aug
2002) and stillbirth (Aug 2006)
Sire effects allow for corrective
matings in heifers to avoid large
calves
MGS effects control against
selection for small animals which
would have difficulty calving
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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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Dystocia and stillbirthDystocia and stillbirth
Meyer et al. (2001) 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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Evaluation conclusionsEvaluation conclusions
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 currently
underway to improve recording of
calf livability
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Index dataIndex data
Same initial dataset as BV estimation
Calvings with unknown MGS were
eliminated for VCE
Records with sire and MGS among the
2,600 most-frequently appearing bulls
were selected
2,083,979 calving records from 5,765
herds and 33,304 herd-years
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SamplingSampling
Six datasets ofSix datasets of ~250,000~250,000 records each wererecords each were
created by randomly sampling herd codescreated by randomly sampling herd codes
without replacementwithout replacement
Datasets ranged fromDatasets ranged from 239,192239,192 toto 286,794286,794
observations, and all averagedobservations, and all averaged 7%7% stillbirthsstillbirths
A common pedigree file was used to facilitateA common pedigree file was used to facilitate
comparisons between sire and MGS solutionscomparisons between sire and MGS solutions
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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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Economic assumptionsEconomic assumptions
Newborn calf value
Expenses per difficult birth (CE ≥4)
$450 for females
$150 for males
$75 labor and veterinary
$100 reduced milk yield
$75 reduced fertility and longevity
1.5% chance of cow death ($1800)
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Calving Ability indexCalving Ability index
CA$ 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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Breeds other than HolsteinBreeds other than Holstein
Brown Swiss economic values are
−6 for SCE and −8 for DCE
• Separate SB evaluations are not
available
• CE values include the correlated
response in SB
Other breeds will be assigned CA$
of 0
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Health and calving traitsHealth and calving traits
Health event data from on-farm
computer systems
Events arranged in putative causal
order by DIM at first occurrence
Path analysis to determine
associations among disorders
Significant associations shown in
following tables (P < 0.05)
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Health and dystociaHealth and dystocia
Disorder DIM Odds Ratio
Stillbirth 1 39.0
Retained placenta 1 3.8
Mastitis (0—30 d) 6 2.3
Ketosis 11 3.1
Metritis 16 3.9
Reproductive 32 2.3
Displaced abomasum 29 2.2
Respiratory 44 3.0
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Health and stillbirthHealth and stillbirth
Disorder DIM Odds Ratio
Retained placenta 1 2.8
Mastitis (0—30 d) 6 2.4
Metritis 16 2.1
Displaced abomasum 30 2.3
Reproductive 32 3.4
Digestive 52 2.8
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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
The US participates in routine Interbull
evaluations that began in November 2006
Calving problems increase lifetime health care
costs and decrease profitability
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AcknowledgmentsAcknowledgments
Jeff Berger, Iowa State University
John Clay, Dairy Records Management
Systems
Ignacy Misztal and Shogo Tsuruta,
University of Georgia
National Association of Animal Breeders