Increasing pedigree contribution to dairy sire evaluation

Methods to improve contributions of ancestor information to sire evaluations computed by the Modified Contemporary Comparison were studied. Pedigree index (one-half evaluation of sire plus one-fourth evaluation of maternal grandsire ) was used to indicate ancestor merit with adjustment for type of sampling program and birth date. For Holsteins, effect of sampling through artificial insemination was 35 kg for milk yield; effect of birth date (trend of daughter merit not accounted for by pedigree index or type of sampling) was 7.3 kg/yr for milk yield and .36 kg/yr for fat yield. Trends were larger for milk and fat yields of Ayrshires , Brown Swiss, Guernseys , and Jerseys except for fat yield of Ayrshires , which had no significant trend. Correlations of daughter merit with pedigree index and with present group average (average daughter merit of bulls with similar pedigree indexes for milk yield) were computed. For milk yield, correlations of daughter merit with pedigree index and with group average were nearly the same; however, for fat yield, pedigree index had a higher correlation with daughter merit than did group average. Accounting for residual trend resulted in further increase of correlation. Replacing one-fourth evaluation of maternal grandsire with one-half Cow Index of dam also improved correlations slightly. Evaluations can be modified so that pedigree index adjusted by birth date replaces group average in representing ancestor merit. Such evaluations better predict performance of future daughters than do evaluations with grouping by pedigree index for milk yield, particularly for evaluations for fat yield. Dam's Cow Index provides little additional information.