selection for fertility in dairy cattle
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Selection for Fertility in Dairy Cattle. Factors Affecting Fertility. Environment and management Season, region, herd, age, milk yield Estrus detection and / or synchronization Voluntary waiting period Fertility of bull (ERCR in USA) Genes of cow (Dau. Pregnancy Rate)

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Presentation Transcript
factors affecting fertility
Factors Affecting Fertility
  • Environment and management
    • Season, region, herd, age, milk yield
    • Estrus detection and / or synchronization
    • Voluntary waiting period
  • Fertility of bull (ERCR in USA)
  • Genes of cow (Dau. Pregnancy Rate)
  • Interaction of bull’s and cow’s genes
    • Inbreeding, recessives (CVM, DUMPS)
fertility does not show
Fertility Does Not Show

Paul VanRaden,

1974

for fertility you need data
For Fertility, You Need Data

Paul VanRaden,

1995

pregnancy rate
Pregnancy Rate
  • The percentage of nonpregnant cows that become pregnant during each 21-day time period
  • Pregnancy rate < conception rate
    • Cows that are not cycling
    • Estrus not expressed or detected
  • Typical pregnancy rates
    • 20% if calving interval is 14.3 months
    • 25% if calving interval is 13.6 months
pregnancy rate and days open
Pregnancy Rate and Days Open

100

90

80

70

60

Pregnancy Rate

50

40

30

20

10

1

2

3

4

5

6

7

8

9

0

60

81

102

123

144

165

186

207

228

249

Number of Chances

Days Open

distribution of days open holstein calvings 1990 2001
Distribution of Days OpenHolstein Calvings 1990 - 2001

Cows culled for reproductive reasons

≤ 50

≥ 250

usa fertility evaluation
USA Fertility Evaluation
  • Holstein data in evaluation
    • 44 million lactation records since 1960
    • 17 million cows
    • Lactations 1-5 are included
  • Reliability for recently proven bulls
    • 59% REL for Daughter Pregnancy Rate
    • 61% REL for Productive Life
    • 69% REL for Somatic Cell Score
    • 85% REL for Milk Yield
usa evaluation methods
USA Evaluation Methods
  • Animal model, introduced Feb 2003
    • Same programs as yield, PL, SCS
    • Compare cows within herd, season, and age
    • Convert days open to pregnancy rate = (233 – DO) / 4
  • Parameter estimates used:
    • Heritability = 4%
    • Repeatability = 11%
    • Sire-by-herd interaction = 4%
recent usa changes november 2003 and november 2004
Recent USA ChangesNovember 2003 and November 2004
  • Earlier evaluation of cow fertility
    • Records in progress used at 130 instead of 250 days in milk
    • Pregnancy exams used in prediction
    • 6% gain in REL of DPR for new bulls
  • Fertility used to predict longevity
    • 4% gain in REL of PL for recent bulls
selection for longevity
Selection for Longevity
  • Productive Life introduced in USA in 1994 to select for longevity
  • Genetic correlations with other traits:
    • Daughter pregnancy rate = .59
    • Somatic cell score = -.35
    • Udder composite = .30
    • Daughter calving ease = -.24
value of cow fertility
Value of Cow Fertility
  • Fertility expenses per day open
    • Heat detection ($20 / lact  .005) = $.10
    • Semen ($15 / unit + $5 labor) *.025 = $.50
    • Pregnancy exam ($10 / exam)*.012 = $.12
    • Lactations too long or short = $.75
  • Value of DPR as % of total economic value
    • 7% in Net Merit since August 2003
    • 5% in TPI since February 2005, also
    • -2% for dairy form in TPI since February 2005
days open genetic correlations jorjani 2005 interbull bulletin
Days Open Genetic Correlations Jorjani, 2005 Interbull Bulletin

DFS = Denmark-Finland-Sweden

conclusions
Conclusions
  • Fertility traits are less heritable but more variable than yield and type
  • Selection for high yield reduces fertility
  • Selection for longevity increases fertility
  • Cow fertility traits receive 2% to 13% of total selection in many countries
  • Bulls that sire good fertility are available
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