Predictability of Pedigree Indexes for Bulls from Two, Three, and Four Generations

Pedigree indexes were calculated from two, three, and four generations for subsets of 380 Holstein bulls that had been progeny tested. Traits indexed were milk, fat, and type. Only male ancestors were considered. Regression coefficients of Predicted Difference and contemporary deviation on pedigree index usually were highest for pedigree index from three generations for milk and fat. Rank correlations of pedigree indexes from two and three generations were .95 to .98 but from three and four generations were .99 to 1.00. Maternal great-grandsires had detectable influence on genetic merit of bulls even though contribution was small as expected. Maternal great-great-grandsires did not contribute to predictability of pedigree indexes.