Genetic selection for reproduction
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Genetic selection for reproduction:. Current reproductive status of the national herd;. Application of selection indexes for dairy producers. 2007. Current reproductive status of the national herd. H.D. Norman. Dairy Cattle Reproductive Council Convention ( 2 ). Bull fertility.

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Genetic selection for reproduction

Genetic selection for reproduction:

Current reproductive statusof the national herd;

Application of selection indexesfor dairy producers


Genetic selection for reproduction

2007

Current reproductive statusof the national herd

H.D. Norman

Dairy Cattle Reproductive Council Convention (2)


Bull fertility

Bull fertility

  • Estimated Relative Conception Rate (ERCR)

    • 70-day nonreturn rate (NRR)

    • Phenotypic evaluation

    • Source:

      • DRMS (Raleigh, NC), 1986−2005

      • USDA (Beltsville, MD), 2006−present

  • Western Bull Fertility Analysis

    • 75-d veterinary-confirmed conception rate

    • Source: AgriTech (Visalia, CA), 2003 −present


Ercr distribution aug 2007

ERCR distribution (Aug. 2007)


Survey of ai organizations

Survey of AI organizations

  • Does your organization rate bulls on fertility from field data?

  • Where do you obtain the data you use to evaluate them?

  • How long a time period is included in your evaluation?

  • What do you publish?

  • How many nonreturn days are in your calculation?

  • Is your evaluation derived from first or all services?

  • Do you eliminate cows sold before a specific number of days after insemination?

  • Do you eliminate cows in herds that go off test before a specific number of days after insemination?

  • Is information on services from natural service bulls that follow AI breedings available to you to document failures of those AI breedings?


Survey results

Survey results

  • All had programs to monitor bull fertility, but few relied completely on in-house information

    • Most received some information from technician breedings

    • One purchased breeding records from a dairy records processing center

    • Another obtained breeding records directly from cooperating herds

  • Most common fertility measure was NRR

    • Varied from 59 to 90 days for first breeding

    • Some organizations used a range of days


Survey results cont

Survey results (cont.)

  • Conception rate (CR) used by one because of availability of pregnancy-check records

  • Time period for data included in a bull’s fertility evaluation varied from 1 year to no limit

  • Equal number included only first services compared with all services

  • Data from technician breedings

    • Not adjusted for cow departures because of culling or when a herd discontinued production testing

    • No access to data that showed when natural service followed an AI mating


New usda service sire evaluation

New USDA service sire evaluation

  • Based on conception rate rather than NRR

  • More accurate

    • Inseminations from most of the United States

    • All services (not just first)

    • Additional model effects included

  • Available early 2008

  • Documentation at ftp://aipl.arsusda.gov/pub/outgoing/BullFert/


Cow fertility trends

Cow fertility trends


Cow fertility trends1

Cow fertility trends


Cow fertility trends2

Cow fertility trends


Cow fertility trends3

Cow fertility trends


Parity averages 2005 breedings

Parity averages (2005 breedings)


Parity averages 2005 breedings1

Parity averages (2005 breedings)


Parity averages 2005 breedings2

Parity averages (2005 breedings)


Parity averages 2005 breedings3

Parity averages (2005 breedings)


Holstein nrr 2005 breedings

Holstein NRR (2005 breedings)


Holstein cr 2005 breedings

Holstein CR (2005 breedings)


Holstein regional averages 2005 breedings

Holstein regional averages (2005 breedings)


Holstein regional averages 2005 breedings1

Holstein regional averages (2005 breedings)


Holstein regional averages 2005 breedings2

Holstein regional averages (2005 breedings)


Holstein regional averages 2005 breedings3

Holstein regional averages (2005 breedings)


Pregnancy rate pr

Pregnancy rate (PR)

  • Percentage of nonpregnant cows that become pregnant during each 21-day period

  • Advantages over days open (DO)

    • Easily defined

    • Information from nonpregnant cows included more easily

    • Larger (rather than smaller) values desirable

  • PR = [21/(DO − voluntary waiting period + 11)]100

    • Voluntary waiting period assumed to be 60 days

    • Factor of +11 adjusts to middle day of 21-day cycle

  • Examples

    • Herd with average of 133 DO has PR of 25%

    • Herd with average of 154 DO has PR of 20%


Holstein regional averages 2005 breedings4

Holstein regional averages (2005 breedings)


Herds with synchronized breeding

Herds with synchronized breeding


Current breed averages

Current breed averages


Usda pregnancy rate

USDA pregnancy rate

  • Linear approximation

  • PR = 0.25 (233 − DO)

  • 1% higher PR = 4 days fewer open


Daughter pregnancy rate dpr

Daughter pregnancy rate (DPR)

  • First USDA genetic evaluations in 2003

  • Same across-breed animal model as for yield traits, productive life (PL), and somatic cell score (SCS)

  • Heritability of 4%

  • Predicted transmitting abilities (PTAs) reported as percentages

    • Daughters of bull with PTA DPR of 1 expected to be 1% more likely to become pregnant during estrous cycle than if bull had PTA DPR of 0

    • Each increase of 1% in PTA DPR equivalent to decrease of 4 days in PTA DO

  • PTA DO approximated by −4 × PTA DPR

  • Example: Bull with PTA DPR of +2.0 would have PTA DO of −8


Dpr trend august 2007 base

DPR trend (August 2007 base)


Bull pta dpr frequency aug 2007

Bull PTA DPR frequency (Aug. 2007)


Genetic selection for reproduction

NM$

CY$

PTI

FM$

2007

Application of selection indexesfor dairy producers

H.D. Norman

Dairy Cattle Reproductive Council Convention (31)


Lifetime merit indexes

Lifetime merit indexes


Genetic merit of high dpr holstein bulls

Genetic merit of high-DPR Holstein bulls


Genetic merit of high dpr holstein bulls1

Genetic merit of high-DPR Holstein bulls


Genetic merit of high dpr holstein bulls2

Genetic merit of high-DPR Holstein bulls


Genetic merit of high dpr holstein bulls3

Genetic merit of high-DPR Holstein bulls


Genetic merit of high dpr holstein bulls4

Genetic merit of high-DPR Holstein bulls


Dpr benefits over productive life

DPR benefits over productive life

  • Additional calves produced

  • Decreased units of semen needed per pregnancy

  • Decreased labor and supplies for heat detection, inseminations, and pregnancy checks

  • Higher yields because more ideal lactation lengths


Lifetime value

Lifetime value

  • Factors in determining economic value

    • Loss of about $1.50/DO

    • 2.8 lactations per cow

    • No breedings for half of cows during final lactation

    • Correlation of heifer and cow fertility (0.3)

    • Value of extra calves

    • Other unmeasured health expenses

  • Total lifetime merit value of $21/PTA DPR unit


Total performance index tpi

Total Performance Index (TPI)

  • Calculated by Holstein Association USA (Brattleboro, VT)

  • Emphasis of 19% on early breeding

    • 10% on PL

    • 8% on DPR

    • −1% on dairy form

  • 95% correlation between USDA lifetime net merit and Holstein TPI


Genetic selection for reproduction

2007

Conclusions

H.D. Norman

Dairy Cattle Reproductive Council Convention (41)


Service sires

Service sires

  • Using bulls with higher conception rates returns profit fairly quickly

    • Premium of $2 could be paid for semen per 1% improvement in fertility

    • Unit of semen from bull with ERCR of +2 worth $8 more than unit from bull with ERCR of −2

  • Little genetic improvement in male fertility expected over time

  • Use bull fertility as a secondary selection trait after production and economic indexes


Selection for cow fertility

Selection for cow fertility

  • Selection for improved fertility possible and recommended

  • Most benefits delayed for 2 years or more

  • Select service sires for overall lifetime merit that includes daughter fertility rather than for daughter fertility alone

  • Producers with herd fertility problems may choose to emphasize DPR extensively, which can be done with little loss in overall net merit


Benefits of improved reproduction

Benefits of improved reproduction

  • Lower semen cost

  • Improved ability to optimize lactation and lifetime yields

  • Reduced culling due to delayed or failed conception

  • More herd replacements


Fertility emphasis

Fertility emphasis

  • Service-sire fertility and DPR important for all management systems, but most important for grazing herds with seasonal calving

  • Use of a few bulls that average 3.0% for PTA DPR (equivalent to a decrease of 12 DO) could recover much of genetic decline in fertility from use of high-yield bulls for 40 years

  • General recommendation still is to select for overall merit based on genetic-economic index appropriate for current milk market


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