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Characteristics of genetic evaluations for daughter fertility in relation to other fitness traits

Characteristics of genetic evaluations for daughter fertility in relation to other fitness traits. Abstr. 519. DHI-Provo lactation records. Economic impact. Lower herd milk yield Increased insemination costs Losses from involuntary culling for fertility International export disadvantage.

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Characteristics of genetic evaluations for daughter fertility in relation to other fitness traits

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  1. Characteristics of genetic evaluations for daughter fertility in relation to other fitness traits Abstr. 519

  2. DHI-Provo lactation records

  3. Economic impact • Lower herd milk yield • Increased insemination costs • Losses from involuntary culling for fertility • International export disadvantage

  4. Data donors • Dairy Records Management Systems Raleigh, NC • AgSource Cooperative Services Verona, WI • AgriTech Analytics Visalia , CA • Pennsylvania DHIA Service Center University Park, PA

  5. Reproductive traits • Days to 1st breeding • Service period • Percentage of nonreturn to 1st service • Services per conception • Days open

  6. Pregnancy rate (PR) • Percentage of nonpregnant cows that become pregnant during next 21 d • Derived from days open: PR = (233 – days open) / 4

  7. Selection for fertility? • Pessimistic • R.H. Foote, 1969, JDS • R. Nebel, 2003, Holstein International • Optimistic • Norman et al., 2003, ADSA meeting

  8. Coefficients of variation (CV) DPR = daughter pregnancy rate, PL = productive life, SCS = somatic cell score

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

  10. Objectives • Compare evaluation characteristics • DPR • Other recent fitness traits • Determine appropriate perspective for use of current genetic tools

  11. Genetic trend: DPR

  12. Genetic trend: SCS, PL

  13. Mean cow reliability (%)

  14. Heritability (%)

  15. Mean bull reliability (%)

  16. Birth year and AI organization • Effect on PTA variation: • No differences among AI organizations for DPR, but an effect found for PL and SCS

  17. Conclusions • DPR reliability comparable to reliabilities for other fitness traits • DPR should be included in all aspects of genetic programs to reverse decline in reproductive performance • Little difference in DPR among AI organizations • If fitness traits receive 50% of weight in future net merit indexes, acceptance of lower reliability will become more common

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