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Genetic Evaluations for Fitness and Fertility in the US and Other Nations

Discover key traits affecting milk production costs, fertility rate predictions, and optimal days open for cow fertility. Explore genetic correlations, fertility expenses, and national selection indexes for improved breeding strategies.

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Genetic Evaluations for Fitness and Fertility in the US and Other Nations

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  1. Genetic Evaluations for Fitness and Fertility in the US and Other Nations

  2. Which Traits? • “A key priority in research and education should be to identify those traits that really affect cost of producing milk and concentrate selection on them” (McDaniel, 1976 National Workshop) • Still good advice today

  3. Genetic progress G = accuracy  genetic SD  selection intensity  generation interval (Dickerson & Hazel, 1944)

  4. Heritability of N Records= N h**2 / [1 + (N – 1) Repeatability](Lush, 1948)

  5. Average accuracy= square root of reliability / 100

  6. Coefficients of variation (CV) DPR = daughter pregnancy rate, PL = productive life,

  7. Trait HarmonizationMark, 2003 EAAP meeting

  8. MACE Longevity CorrelationsJakobsen, 2003 Interbull meeting

  9. MACE for Calving EaseJakobsen, 2003 Interbull meeting

  10. Pregnancy Rate • Rate that cows become pregnant • Can be derived from days open • Non-linear: 21 / (DO – VWP + 11) • Linear approx: (233 – DO) / 4 • Advantages over days open • Positive numbers are desirable • Earlier measure of herd fertility

  11. Pregnancy Rate vs 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

  12. Cow Fertility Traits Evaluated in Largest Holstein Populations

  13. Prediction of UK Calving IntervalWall et al, 2003 Interbull meeting

  14. International Fertility Correlations • UK, DEU, FRA, NLD (Wall, 2003) • Non-return, PTA correlation avg = .54 • DNK, FIN, SWE(Mark, 2001) • Days to 1st AI, genetic cor avg = .67 • Non-return rate, genetic cor avg = .44 • Ayr from NOR, DNK, FIN, SWE(Svendsen, 2001) • Fertility index, genetic cor avg = .73

  15. Value of Cow Fertility • Optimum days open • Pregnancy rate affects mean and variance • Reduced yield/day vs longer lactations • 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 • Relative value of DPR = 7% of total

  16. Value of Calving Ease • Daughter CE value / difficult birth • Veterinary, labor costs = $50 • Calf death (20% prob) = $25 • Cow deaths before 1st test (1% prob) = $15 • Service sire CE also includes • Yield losses / lactation = $40 • Fertility and longevity losses = $30 • Relative values of each are 2% of total

  17. National Selection Indexes:Yield and Health Traits

  18. National Selection Indexes:Conformation and Management Traits

  19. Response to NM$ Selection

  20. Changes for November 2003 • Earlier evaluation of DPR • Records in progress used at 130 instead of 250 DIM • 6% gain in REL of DPR for new bulls • Developed by Melvin Kuhn • Use of DPR, SCE, DCE to predict PL • 4% gain in REL of PL for recent bulls

  21. Conclusions • Most fitness traits are less heritable but more variable than yield and type • In August 2003 NM$, cow fertility receives 7% and calving ease traits each receive 2% of total selection • Reasonable progress is expected • National fitness trait evaluations need to reach foreign customers

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