Alternatives for evaluating daughter performance of progeny-test bulls between official evaluations
H. D. Norman*¹, J. R. Wright¹, K. A. Weigel²; Animal Improvement Programs Laboratory, ARS, USDA, Beltsville, MD, USA¹, Department of Dairy Science, University of Wisconsin, Madison, WI, USA²

In August 2007, USDA changed from calculating official genetic evaluations quarterly to triannually to coincide with the schedule for international evaluations. Industry cooperators requested that unofficial interim evaluations be initiated between official evaluations for progeny-test (PT) bulls to offset part of the delay in receiving information due to the schedule change. To determine whether interim evaluations could provide accurate information for semen collection and storage (banking) for bulls of potentially superior genetic merit, interim evaluations were calculated with the current USDA animal model system and 4 data subsets of milk yield records from daughters of Holstein PT bulls with official August 2006 evaluations: 1) most recent 12 mo of calvings from cooperator herds with ≥1 PT daughter, 2) most recent 18 mo of calvings from herds with ≥1 PT daughter, 3) most recent 12 mo of calvings from herds with ≥5 PT daughters, and 4) most recent 18 mo of calvings from herds with ≥5 PT daughters. Interim evaluations from each data subset were compared with previous and subsequent official USDA evaluations. Correlations between interim and official evaluations were high (0.95 to 0.98 for bulls of interest) for all 4 subsets, which indicated that interim evaluations could provide valuable information between official evaluations. Correlations were highest when data were included from the most recent 18 mo of calvings from herds with ≥1 PT daughter. Interim evaluations had a higher reliability than that of previous official evaluations for almost all PT bulls that added daughters and had a lower reliability for almost all non-PT bulls. The Council on Dairy Cattle Breeding and dairy records processing centers supported June, September, and November interim evaluation with release limited to PT bulls with ≥10 daughters and an increase in reliability since the most recent official sire evaluation.

KEYWORDS
interim evaluation
genetic evaluation
progeny test