Data were production and herdlife information from herds participating in the Holstein Association of America classification program. Cows were divided into two data sets based on registry status. Production and herdlife information from all cows freshening for the first time in the same herd-year in classified herds indicated that the registered cows that were classified were not a random sample of their herds. Genetic and phenotypic (co)variances among linear type traits, final score, first lactation milk and fat yields and productive life to 84 month were estimated with a multiple trait sire model for both registered and grade populations. Maximum accuracy of prediction of herdlife from the linear type traits was much higher in the registered analysis (59%) than in the grade analysis (25%). Addition of milk production to prediction raised the maximum accuracy in the grade analysis to 71%, while the maximum accuracy in the registered analysis was raised to 68%. Similar results were observed in using correlations from a previous study. These results suggest that accuracy of evaluation of herdlife from the linear type traits is dependent on registry status, previous selection of the data for yield or a combination of these effects.

D. J Weigel, B. G Cassell

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 17. Genetics and breeding of dairy and beef cattle, swine and horses, , 73–76, 1994
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