RELATIONSHIP BETWEEN BULL DAM HERD CHARACTERISTICS AND BIAS IN ESTIMATED BREEDING VALUE OF BULL

The objective of the study was to relate estimated breeding values (EB Vs) of the parents' 305-days protein production and the bull dam herd- year characteristics to the empirical bias in pedigree indices (differ ence between the pedigree index and the final proof) of young bulls. T wo animal model evaluations were carried out; one included records up to 1990 and the other up to spring 1992. The final data set included 2 42 bulls with pedigree indices, final proofs, parents' EBVs, productio n and herd information (the size, the average production and the intra herd standard deviation) of the darns. The average empirical bias in p edigree indices was 13.6 kg. The correlation between the final proof o f the bull and the EBVs of the bull sire or dam were 0.45 and 0.17, re spectively. The low correlation with bull dam EBV indicates the unreli ability of the bull dam EBVs. Size of the herd and the standard deviat ion of production in the herd when bull dam produced its third lactati on were correlated with the empirical bias in pedigree index. Pedigree indices of the bulls coming from small herds with high intraherd stan dard deviation were more biased than those from the big herds with low intraherd standard deviation. The best bulls, when grouped according to their final proofs, were sons of the highest EBV sires. EBVs of bul l dams did not differ in the highest and the lowest final proof groups , but the dams of the best bull group had a higher first lactation rec ord than the dams of the other bull groups.