By Ashley Sanders
Several changes were made in the data editing process for records included in the daughter pregnancy rate (DPR) evaluations. Previously, only the final lactation records for cows calving since 2000 were considered for prediction of actual days open using the prediction model described in Changes to Evaluation System - November 2003. Beginning in November 2004, any calvings since 1990 with 130 to 249 DIM that do not have calculated calving interval available (because the subsequent freshening was unreported or the result of an abortion) will be considered using the same criteria as records in progress (RIP). Also, the exclusion of lactation records of embryo donors applied to the first lactation in which a cow is a donor and all subsequent lactations, will be based on embryo donation reported in a format 5 record in addition to the birth records of ET progeny. Herds that do not report breeding information can create bias when considering recent lactations (when only cows with shorter days open would have had a subsequent calving from which to calculate days open), or the most recent lactations for a herd (i.e. RIPs which depend on a prediction model for estimating days open). In these cases, the herd must have breedings reported for at least 50% of the calvings in the same year (or the previous year when considering the current calendar year) for a record to be included in evaluations. In addition to these changes, the identification of cows with usable first lactation records for DPR was clarified. Cows must have a first lactation yield record as well as a usable first lactation days open record to be evaluated for DPR.
By George Wiggans
Equations for predicting days open for cows with between 130 and 249 DIM without a subsequent calving were revised to give different predictions for cows confirmed pregnant, confirmed open, or with unknown pregnancy status. Pregnancy status was not included in the available data when the previous system was developed. Reporting of pregnancy status began in 2002 and for 2003–2004 calvings, approximately 70% of records include this information. The largest difference was for lactations confirmed open. The previous system under predicted the days open by over 96 days for the lactations between 130 and 149 DIM. Lactations for this DIM interval with a confirmed pregnancy were previously over predicted by 18 days.