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Comparison of Service-Sire Fertility Evaluations in US Dairy Industry

This study compares the former and current methods of estimating relative conception rate (ERCR), Western Bull Fertility Analysis (WBFA), and Sire Conception Rate (SCR). The methodology differences, number of bulls, mean number of matings per bull, and correlations between methods are analyzed. The conclusions highlight the availability of SCR evaluations for a larger number of bulls, slightly higher standard deviation of Holstein SCR, and higher correlations between consecutive SCR evaluations.

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Comparison of Service-Sire Fertility Evaluations in US Dairy Industry

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  1. WBFA SCR ERCR Comparison of service-sire fertility evaluations formerly or currently available to the US dairy industry Abstr. 31

  2. Former and current methods • Estimated relative conception rate – ERCR • 1986 (Dairy Records Management Systems) • Western Bull Fertility Analysis – WBFA • 2003 (AgriTech Analytics) • Sire conception rate – SCR • 2008 (USDA)

  3. Methodology differences • ERCR • 70-d nonreturn rate • Minimum of 300 matings/bull for release • Included only first services for Holsteins and Jerseys • WBFA • Bull conception rate based on confirmed pregnancies • Minimum of 10 matings/bull in 10 herds • Includes services 1 through 5 for Holsteins and Jerseys • SCR • 10 effects to predict bull conception rate • Minimum matings/bull during last 4 yr • 300 for Holsteins; 100 or 200 for other breeds • Includes services 1 through 7 for all US breeds

  4. SCR bull variables • Inbreeding • Service sire • Embryo • Bull age • AI organization combined with mating year • Bull

  5. Data • Holstein and Jersey bulls • January and April 2009 evaluations from same herds • Processing centers • Agritech Analytics (ERCR, WBFA, SCR) • AgSource (ERCR, SCR) • DRMS (ERCR, SCR)

  6. Number of bulls

  7. Mean number of matings/bull

  8. Means ± SD

  9. Number of bulls by age – April 2009

  10. Means by bull age – April 2009

  11. SD by bull age – April 2009

  12. Correlations between methods*

  13. Correlations – January/April evaluations

  14. Change between evaluations

  15. Conclusions • SCR evaluations available for over twice as many bulls as ERCR and WBFA • SD of Holstein SCR (2.4) slightly higher than SD of ERCR and WBFA (1.9 to 2.0) • Holstein correlations of SCR with ERCR (0.7) and WBFA (0.6) higher than correlation of ERCR with WBFA (0.5) • Higher correlations between consecutive evaluations for SCR (0.96 to 0.98) than for ERCR and WBFA (0.93 to 0.94)

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