Modified Contemporary Comparison as a Predictor for Future Daughters

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Abstract
Modified Contemporary Comparisons of sires from United States Department of Agriculture files were searched to locate bulls summarized in Oct., 1974, with substantial additional information in a subsequent sire summary. The summary of Oct., 1974, and the latest subsequent summary through Jan., 1976, on 702 Holstein bulls were used to develop a measure of daughter performance from information added between summaries on each sire. Predicted Differences of milk, fat, and 72 other variables from the Oct., 1974, summary were independent variables for prediction of performance of additional daughters for milk and fat. The best predictive equation for performance of additional daughters for milk included Predicted Difference for milk, fraction culled, and Repeatability times contemporary fathers'' Modified Contemporary Deviation for milk, Predicted Difference for milk alone accounted for 94.3% as much of the predictable variation as did the entire predictive equation. Analysis of fat production of additional daughters provided similar evidence for the predictive value of Predicted Difference for fat. Analysis of sire summaries of 1st lactation, including data through May, 1976, verified results. Predicted Difference for milk and fat from multi-herd proofs appear to be sufficiently accurate predictors of performance of future daughters to serve as sole criterion of selection for production in breeding programs.