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2006 J.B. Cole Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD jcole@aipl.arsusda.gov@aipl.arsusda.gov Genetic Evaluation of Calving Traits in US Holsteins
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CSU 2006 – Breeding and Genetics Seminar (2) Cole 2006 Introduction A national evaluation was implemented for calving ease (CE) in August 2002 and for stillbirth (SB) for Holstein in August 2006. A calving ability index (CA$) which includes SB and calving ease (CE) was developed. Some challenges with the CE and SB evaluations remain
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CSU 2006 – Breeding and Genetics Seminar (3) Cole 2006 History 1977 – NAAB-sponsored evaluations within AI organizations 1980 – NAAB-sponsored evaluations across AI organizations 1988 – Ordered categorical threshold model 1990 – Semiannual evaluations 1999 – Processing change from Iowa State University to USDA (November) 2002 – Sire-maternal grandsire (MGS) model
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CSU 2006 – Breeding and Genetics Seminar (4) Cole 2006 Threshold model Scores assumed to be observations on a continuous underlying scale Thresholds estimated to relate observed scores to underlying scale Procedure allows for differences in amount of change between consecutive scores Observed scores Underlying scale 51 1 2345
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CSU 2006 – Breeding and Genetics Seminar (5) Cole 2006 Calving 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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CSU 2006 – Breeding and Genetics Seminar (6) Cole 2006 Stillbirth 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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CSU 2006 – Breeding and Genetics Seminar (7) Cole 2006 Distribution of Stillbirth and Calving Ease Scores 7,484,309 29,320348,6775,348,0291,758,283 Total 96,087 1,27232,19638,92923,690 5 207,242 1,74037,851108,03759,614 4 633,029 3,35370,522375,203183,951 3 738,853 2,53749,858482,720203,738 2 5,809,09820,418158,2504,343,1401,287,290 1 Total3210 Calving Ease Score Stillbirth Score
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CSU 2006 – Breeding and Genetics Seminar (8) Cole 2006 Stillbirth Records by Lactation
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CSU 2006 – Breeding and Genetics Seminar (9) Cole 2006 Detecting Stillbirth Data Errors
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CSU 2006 – Breeding and Genetics Seminar (10) Cole 2006 Data 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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CSU 2006 – Breeding and Genetics Seminar (11) Cole 2006 Sire-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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CSU 2006 – Breeding and Genetics Seminar (12) Cole 2006 Genetic 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)
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CSU 2006 – Breeding and Genetics Seminar (13) Cole 2006 Trait 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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CSU 2006 – Breeding and Genetics Seminar (14) Cole 2006 Phenotypic Trend for Stillbirths
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CSU 2006 – Breeding and Genetics Seminar (15) Cole 2006 Genetic Trend for Stillbirths
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CSU 2006 – Breeding and Genetics Seminar (16) Cole 2006 Distribution of PTA
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CSU 2006 – Breeding and Genetics Seminar (17) Cole 2006 Distribution of Reliabilities
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CSU 2006 – Breeding and Genetics Seminar (18) Cole 2006 Dystocia 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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CSU 2006 – Breeding and Genetics Seminar (19) Cole 2006 Evaluation 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 underway to improve recording of calf livability
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CSU 2006 – Breeding and Genetics Seminar (20) Cole 2006 Index Data 7 million SB records were available for Holstein cows calving since 1980 Calvings with unknown MGS were eliminated for VCE Records with sire and MGS among the 2,600 most-frequently appearing bulls were selected
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CSU 2006 – Breeding and Genetics Seminar (21) Cole 2006 Data (cont’d) Herds needed ≥10 calving records with SB scores of 2 or 3 in the database to be included Herd-years were required to include ≥20 records and only single births were used Inclusion of all records for a cow was not guaranteed The final dataset included 2,083,979 calving records from 5,765 herds and 33,304 herd- years
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CSU 2006 – Breeding and Genetics Seminar (22) Cole 2006 Sampling Six datasets of ~250,000 records each were created by randomly sampling herd codes without replacement Datasets ranged from 239,192 to 286,794 observations, and all averaged 7% stillbirths A common pedigree file was used to facilitate comparisons between sire and MGS solutions
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CSU 2006 – Breeding and Genetics Seminar (23) Cole 2006 Bayesian (co)variance components estimates Var(Sire)Var(MGS)Cov(S-MGS) SampleMeanSDMeanSDMeanSD 10.0100.0020.0180.0020.0040.001 20.0070.0020.0170.0020.0050.001 30.0090.0010.0190.0020.0050.001 40.0080.0010.0190.0020.0040.001 50.0080.0010.0180.002 0.001 60.0090.0020.0170.0020.0040.001 Mean0.0090.0020.0180.0020.0040.001
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CSU 2006 – Breeding and Genetics Seminar (24) Cole 2006 Heritabilities Calving Ease (Direct)8.6% Calving Ease (MGS)3.6% Stillbirth (Direct)3.0% Stillbirth (MGS)6.5%
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CSU 2006 – Breeding and Genetics Seminar (25) Cole 2006 Genetic Correlations Among SB and CE Trait CESB DirectMaternalDirectMaternal CE Direct1.000.460.670.25 Maternal1.000.290.63 SB Direct1.000.28 Maternal1.00
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CSU 2006 – Breeding and Genetics Seminar (26) Cole 2006 Economic 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 ($1800)
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CSU 2006 – Breeding and Genetics Seminar (27) Cole 2006 Calving Ability Index CA$ 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)
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CSU 2006 – Breeding and Genetics Seminar (28) Cole 2006 Breeds 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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CSU 2006 – Breeding and Genetics Seminar (29) Cole 2006 Calving Ease Genetic Correlations Service sire above diagonal, daughter below CtryCANDNKFRAITANLDSWEUSA CAN.87.81.70.80.86.75 DNK.84.93.77.86.96.90 FRA.80.74.84.91.88 ITA.58.59.85.60.70.61 NLD.89.81.79.59.89.79 SWE.75.82.89.78.69.86 USA.71.78.93.76.77.87
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CSU 2006 – Breeding and Genetics Seminar (30) Cole 2006 Stillbirth Genetic Correlations Service sire above diagonal, daughter below CtryDNKFINISRNLDSWEUSA DNK.85.82.67.92.70 FIN.82.77.64.82.65 ISR.67.70.73.80.66 NLD.82.77.60.65.63 SWE.88.92.65.73.64 USA.81.87.60.71.87
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CSU 2006 – Breeding and Genetics Seminar (31) Cole 2006 Brown Swiss Calving Ease Service sire correlations above diagonal, daughter below CtryCHEDEUNLDUSA CHE.83.81.68 DEU.61.77.67 NLD.89.76.79 USA.70.61.76
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CSU 2006 – Breeding and Genetics Seminar (32) Cole 2006 Index Conclusions 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 included in the September 2006 Interbull test run The US will participate in routine Interbull evaluations beginning in November 2006
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CSU 2006 – Breeding and Genetics Seminar (33) Cole 2006 Recent Calving Ease Research
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CSU 2006 – Breeding and Genetics Seminar (34) Cole 2006 Abnormal Herd-Years Many herd-years have abnormal distributions of scores Two recent approaches to problem Eliminate HY based on GoF tests Collapse categories when mode > 1 Both strategies improve prediction of later evaluations by earlier
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CSU 2006 – Breeding and Genetics Seminar (35) Cole 2006 An Illustration Herds with unusual distributions of data affect evaluations of bulls Worst case is when large share of records for a bull are in one “bad” herd Herd reporting changes over time
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CSU 2006 – Breeding and Genetics Seminar (36) Cole 2006 Test Edits - 2 GoF statistics Based on multinomial distributions Independent of herd size
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CSU 2006 – Breeding and Genetics Seminar (37) Cole 2006 Percentage of Score by Parity In All (AN) and GoF Excluded (AG) Herds 0 10 20 30 40 50 60 70 80 90 100 12345 Calving Ease Score Counts by Herd-Parity (%) Parity 1 - AN Parity 2 - AN Parity 1 - AG Parity 2 - AG
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CSU 2006 – Breeding and Genetics Seminar (38) Cole 2006 Collapse Categories The mode for CE scores in a herd is expected to be 1, but was higher for nearly 10% of data Data from herd-years with a mode of 4 or 5 (1.2%) were deleted A mode of 3 is assumed to indicate that the scorer normalized the data (middle score of 3 for an 'average' birth)
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CSU 2006 – Breeding and Genetics Seminar (39) Cole 2006 Collapse Categories Herds with a mode of 2 or 3: scores up to the mode were changed to 1, and scores greater than the mode were decreased accordingly Herd-years with a mode of 3: scores 1-3 all become 1, scores of 4 are changed to 2, and scores of 5 are changed to 3 Combining categories lowered the portion of difficult calvings and increased the impact of the subsequent goodness-of-fit test Overall, 6.4% of data were excluded
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CSU 2006 – Breeding and Genetics Seminar (40) Cole 2006 Conclusions Exclusion of herds with poor distributions improves prediction of future evaluations across birth years Correlations across all data increased from.66 to.68 Herds with poor score distributions were excluded uniformly across herd size Exclusion of herds results in loss of evaluations for some bulls
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CSU 2006 – Breeding and Genetics Seminar (41) Cole 2006 Separate Parity Effects First and later parities currently modelled as a single trait cblup90iod only accepts one threshold trait Options for bivariate analysis Gibbs sampling (thrgibbs1) Linearization (airemlf90) RR on parity (cblup90iod)
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CSU 2006 – Breeding and Genetics Seminar (42) Cole 2006 Results RR on a 0-1 parity effect does not account for heterogeneous variances GS and AIREML solutions were similar GS required more processing time than is desirable for routine national evaluations The impact of the approximation necessary to linearize the scores is not known Implementation of a bivariate analysis is desirable, but challenging
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CSU 2006 – Breeding and Genetics Seminar (43) Cole 2006 Acknowledgments Jeff Berger, Iowa State University John Clay, Dairy Records Management Systems Ignacy Misztal and Shogo Tsuruta, University of Georgia National Association of Animal Breeders
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