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Correlations Among Measures of Dairy Cattle Fertility and Longevity

Correlations Among Measures of Dairy Cattle Fertility and Longevity. Longevity & Fertility Investigation. 1,062,791 c ows born 1992-1994 Daughters of 3080 Holstein sires Progeny tested bulls with > 60 daughters Older bulls to provide ties and relationships Compare two measures of longevity

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Correlations Among Measures of Dairy Cattle Fertility and Longevity

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  1. Correlations Among Measures of Dairy Cattle Fertility and Longevity

  2. Longevity & Fertility Investigation • 1,062,791 cows born 1992-1994 • Daughters of 3080 Holstein sires • Progeny tested bulls with > 60 daughters • Older bulls to provide ties and relationships • Compare two measures of longevity • Productive Life (max 10 mo / lactation) • Lifespan (first calving until death) • Develop new fertility evaluation

  3. Longevity Parameter EstimatesMulti-trait REML Analysis

  4. Cow Fertility DataMulti-trait REML Analysis • First lactation records • Days Open (DO) = Calving interval – 280d • Limits on DO • Lower limit of 50d • Upper limit of 250d • ‘Sold for reproductive problems’ DO = 250d • ‘Sold for other reasons’ DO = 150d (mean) • Cows sold for dairy not included

  5. Fertility Parameter EstimatesMulti-trait REML Analysis

  6. Proposed USDA Fertility Evaluation • Lactations 1-5 beginning with 1960 • Days Open data • Reported DO confirmed with next calving • Exclude most recent 9 months • Reported DO if no next calving • Exclude most recent 9 months • Calving interval – 280 days if no reported DO • Exclude most recent 18 months • Assigned DO = 250 if sold for infertility

  7. Distribution of Days OpenHolstein Calvings 1990 - 2001 Cows culled for reproductive reasons ≤ 50 ≥ 250

  8. Holstein Phenotypic Trend Lactation 5th 4th 3rd 2nd 1st

  9. Proposed Evaluation Methods • BLUP Animal Model • Same programs used for yield, PL, SCS • Adjust for heterogeneous variance • Parameter estimates used: • Heritability = 4% • Repeatability = 11% • Sire-by-herd interaction = 1%

  10. Evaluation Test Run • Holstein data from May 2002 evaluation • 36 million lactations • 14 million cows • Statistics for recent, well-sampled bulls • Born 1994 - 1997 • Milk REL > 80% (mean = 87%) • 4215 Holstein bulls • 314 Jersey bulls

  11. Bull Evaluations

  12. Days Open Trends • Phenotypic trend 1960 - 1998 Holstein: +37 days Jersey: +20 days • Genetic trend 1960 - 1998 Holstein: +17 days Jersey: +9 days • Expected correlated response Milk trend x.38 correlation = +17 days

  13. Reporting of Cow Fertility • Add mean (such as SCS, calving difficulty)? • Reverse scale so positive is desirable? • Possible names and abbreviations • PTA DO Days Open • PTA DPDate Pregnant or Daughter Pregnancy • PTA CFCow Fertility • Report preliminary August 2002 rankings?

  14. Conclusions • Date pregnant has low heritability (~4%) but high genetic correlation with Productive Life (>.5) • May 2002 test successful, November 2002 official evaluations possible • Indirect selection on PL has reduced decline in fertility, but direct selection could increase lifetime profit. • Productive Life preferred over Lifespan

  15. Acknowledgments • Fertility data for the proposed USDA evaluation were prepared by Ashley Sanders • Statistical and graphical analysis of results were provided by Mel Tooker

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