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Title: Technical Note: Changes to herd cutoff date in conception rate evaluations

Author
item Hutchison, Jana
item Vanraden, Paul
item NORMAN, H - Collaborator
item Cole, John

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2012
Publication Date: 2/1/2013
Citation: Hutchison, J.L., Van Raden, P.M., Norman, H.D., Cole, J.B. 2013. Technical Note: Changes to herd cutoff date in conception rate evaluations. Journal of Dairy Science. 96(2):1264-1268.

Interpretive Summary: Fertility evaluations (service-sire conception rate, heifer conception rate, and cow conception rate) have similar opportunity edits. Edits for these traits were recently modified to use the most recent testdate for each herd rather than a constant cutoff date. Using a herd-specific edit improved accuracy of the evaluations by accounting for differing opportunity to confirm pregnancy caused by discontinued testing or differences in herd testing schedules without having to discard a large number of the most recent inseminations.

Technical Abstract: Service-sire conception rate (SCR) evaluations were implemented for the United States in August 2008. Only inseminations from the most recent 4 yr of breeding records are used for SCR evaluations, and all inseminations must have occurred > 70 d before the data submission deadline for an evaluation. In April 2012, edits for SCR were modified to use the most recent testdate for each herd rather than a constant cutoff date for all SCR data. This edit more precisely measures the days of opportunity for a cow to be diagnosed as pregnant or not pregnant following insemination, and is herd-specific. Number of inseminations before the edit change was 16,906,385 compared to 16,492,331 after the edit change. Correlations of SCR before and after the edit change were 0.96 for Holsteins and slightly lower for other breeds, with little change in mean or standard deviation. Weekly mean conception rates after the edit change were more stable for the most recent inseminations. Conception rate was 60% at wk 10 before the constant cutoff date (before edit change) compared to 42% at 10 wk prior to the last herd testdate (after the edit change). Similar edits to SCR are applied to heifer conception rate (HCR) and cow conception rate data (CCR), and were changed in August 2012 to use herd-specific cutoff dates. The HCR and CCR correlations before and after the edit change were 0.99 or higher for all breeds, with little change in mean or standard deviation. The new edits improve accuracy of SCR, HCR, and CCR evaluations by accounting for differing opportunity to confirm pregnancy caused by discontinued testing or differences in herd testing schedules.