genetic evaluation of calving traits in us holsteins

2007

J.B. ColeJ.B. Cole

Animal Improvement Programs LaboratoryAgricultural Research Service, USDA, Beltsville, [email protected]

Genetic Evaluation of Genetic Evaluation of Calving Traits in US Calving Traits in US

HolsteinsHolsteins

LSU 2007 – Animal Sciences Seminar (2) Cole 2007

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.


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Lactations initiated with dystocia have higher risks for other diseases (Cole et al., unpublished data).


How do the evaluations How do the evaluations work?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


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


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.


Distribution of SB and CE ScoresDistribution of SB and CE Scores

7,484,309 29,320348,6775,348,0291,758,283Total

96,087 1,27232,19638,92923,6905

207,242 1,74037,851108,03759,6144

633,029 3,35370,522375,203183,9513

738,853 2,53749,858482,720203,7382

5,809,09820,418158,2504,343,1401,287,2901

Total3210

Calv

ing

Ease

Sco

re

Stillbirth Score


Stillbirth records by lactationStillbirth records by lactation

0

100

200

300

400

500

1980 1990 2000

Birth Year

Num

ber

of R

ecor

ds (

thou

sand

s)

3

2

1


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)


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


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 e m s BM BS PS YS hy y ijklnoprnplonlkjiijklnopr e m s BM BS PS YS hy y ijklnoprnplonlkjiijklnopr e m s BM BS PS YS hy y


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


Phenotypic trend for Phenotypic trend for stillbirthsstillbirths

0

2

4

6

8

10

12

14

1980

1983

1986

1989

1992

1995

1998

2001

2004

Birth Year

% St

illbi

rth

HeifersCowsAll animals


Genetic trend for stillbirthsGenetic trend for stillbirths

5.0

6.0

7.0

8.0

9.0

10.0

1980 1985 1990 1995 2000Birth Year

%SB

H

Direct

Maternal


Distribution of PTADistribution of PTA

0

5

10

15

20

25

30

35

40

%SBH

Perc

ent of

Sco

ress Direct

Maternal


Distribution of reliabilitiesDistribution of reliabilities

0

5

10

15

20

25

30

35

40

45

50

41-4

5

46-5

0

51-5

5

56-6

0

61-6

5

66-7

0

71-7

5

76-8

0

81-8

5

86-9

0

91-9

5

96-9

9

Reliability

Perc

enta

ge

Direct

Maternal


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


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


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


SamplingSampling Six datasets of Six datasets of ~250,000~250,000 records each records each

were created by randomly sampling were created by randomly sampling herd codes without replacementherd codes without replacement

Datasets ranged from Datasets ranged from 239,192239,192 to to 286,794286,794 observations, and all averaged observations, and all averaged 7%7% stillbirths stillbirths

A common pedigree file was used to A common pedigree file was used to facilitate comparisons between sire facilitate comparisons between sire and MGS solutionsand MGS solutions


HeritabilitiesHeritabilities

Calving Ease (Direct)8.6%

Calving Ease (MGS) 3.6%

Stillbirth (Direct)3.0%

Stillbirth (MGS) 6.5%


Genetic correlations among SB Genetic correlations among SB and CEand CE

Trait

CE SB

DirectMaternal

Direct

Maternal

CEDirect 1.00 0.46 0.67 0.25

Maternal 1.00 0.29 0.63

SBDirect 1.00 0.28

Maternal 1.00


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)


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


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


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)


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


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


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


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

genetic evaluation of calving traits in us holsteins

Science

animal sciences seminar

diseases cole

stillbirth sb

calving records

maternal sb

calving difficulty

sb records

sb scores