2007ADSA 2007 (1) H.D. Norman

Effect of service sireand cow sire ongestation length

H.D. Norman,* J.R. Wright, P.M. VanRaden, and J.B. Cole

Animal Improvement Programs LaboratoryAgricultural Research Service, USDABeltsville, MD 20705-2350

dnorman@aipl.arsusda.gov

Abstr. 230

2006ADSA 2007 (2) H.D. Norman 2007

Objectives

Determine effect of bulls on gestation length Service (calf) sire Cow sire

Improve accuracy of predicting calving date

2006ADSA 2007 (3) H.D. Norman 2007

Data sources

Lactation records from dairy records processing centers (DRPCs)

Calving reports from the National Association of Animal Breeders

Pedigree records from breed associations and DRPCs

Breeding records from 2 DRPCs and Minnesota DHIA

2006ADSA 2007 (4) H.D. Norman 2007

Data edits

Inseminations after February 1998 that resulted in parturitions through December 2005 (>5 million calvings)

Animals excluded if <87% breed purity based on AIPL crossbred database

Secondary editing eliminated animals not bred to an identified AI bull

2006ADSA 2007 (5) H.D. Norman 2007

Data

Characteristic

Population

Heifer CowRecords (no.) 311,55

15,245,25

1Herd-years (no.) 17,551 141,008Bulls (no.)

≥100 conceptionsAll (no.) 183 1,830Active AI (no.) 53 103

≥500 conceptionsAll (no.) 61 525Active AI (no.) 22 30

2006ADSA 2007 (6) H.D. Norman 2007

Fixed effects in model

Conception year

Conception herd-year (absorbed)

Conception month

Age within parity

Parturition status (multiple birth, calf gender)

Lactation length

Milk yield

Discrete groups (no.)

4(heifers)

8 (cows)

12

5(heifers)

17 (cows)

8

7

5

2006ADSA 2007 (7) H.D. Norman 2007

Random effects in model

Service sire (direct)

Cow sire (maternal)

Cow

Residual

2006ADSA 2007 (8) H.D. Norman 2007

Analysis

Bulls with ≥100 heifer and ≥100 cow conceptions All bulls (286 service sires, 348 cow sires)

− Heifers− Cows

Active-AI bulls (116 service sires, 54 cow sires)− Heifers− Cows

Repeated for bulls with ≥500 heifer and ≥500 cow conceptions (132 service sires, 105 cow sires)

2006ADSA 2007 (9) H.D. Norman 2007

Gestation length means (d)

Popu-lation

Ayrshire

BrownSwiss

Guernsey Holstein Jersey

Animals with data passing basic edits

Heifers 282 287 285 278 278½

Cows 282 287½ 286 279½ 280

Animals with added requirementof an identified AI service sire

Heifers — 288 — 278 278½

Cows — 288 — 279½ 280

2006ADSA 2007 (10) H.D. Norman 2007

Gestation length SD (d)

Popu-lation

Ayrshire

BrownSwiss

Guernsey Holstein Jersey

Animals with data passing basic edits

Heifers 5.2 6.5 5.8 5.5 5.4Cows 5.5 6.2 5.6 5.7 5.2

Animals with added requirementof an identified AI service sire

Heifers — 5.8 — 5.2 5.0Cows — 5.8 — 5.3 4.9

2006ADSA 2007 (11) H.D. Norman 2007

Fixed effects results

Conception year

Conception month

Age within parity

Parturition status

Lactation length

Milk yield

– Near 0

– Summer calves arrive early

– Younger animals calve sooner

– Animals with twins calve early

– Small negative effect

– Small positive effect

2006ADSA 2007 (12) H.D. Norman 2007

Heritability estimates

Service sire

Cow sire

— 34%

— 12%

2006ADSA 2007 (13) H.D. Norman 2007

Gestation length PTA distribution

2006ADSA 2007 (14) H.D. Norman 2007

Active AI Holstein PTA range

EffectPTApopulation

Gestation length PTA (d)

Shortest Longest

Service sire Heifer −4.2O Man

4.2Mandelin

Cow −5.3Aspiratio

n

5.3Sovereign

Cow sire Heifer −1.5Darren

2.6Silky

Gibson

Cow −2.1 O Man

2.3Shandy

2006ADSA 2007 (15) H.D. Norman 2007

SD (d) of gestation length PTA

EffectPTA population

Bulls with≥100

conceptions

AllActive

AI

Service sire Heifer 1.43

1.42

Cow 1.32

1.38

Cow sire Heifer 0.75

0.74

Cow 0.76

0.65

2006ADSA 2007 (16) H.D. Norman 2007

Heifer-cow PTA correlations

Bull conceptions PTA

Bull status

AllActive

AI

≥100 Service sire 0.96 0.96Cow sire 0.83 0.77

≥500 Service sire 0.98 0.98Cow sire 0.91 0.75

2006ADSA 2007 (17) H.D. Norman 2007

Service sire-cow sire PTA correlations

Bullconceptions

PTApopulation

Bull status

AllActive

AI

≥100 Heifer 0.61 0.37Cow 0.71 0.71

≥500 Heifer 0.49 0.24Cow 0.76 0.72

2006ADSA 2007 (18) H.D. Norman 2007

Conclusions

Bull differences exist and provide an opportunity to change gestation length

Genetic evaluations based on heifers or cows highly correlated for both service sire and cow sire

Genetic evaluations between service sire and cow sire moderately correlated for both heifers and cows

2006ADSA 2007 (19) H.D. Norman 2007

Conclusions (continued)

Genetic and environmental factors that impact gestation length helpful in predicting expected calving date

More research needed to determine potential value of intentional selection for either shorter or longer gestation length in addition to selection for calving ease and stillbirth