GENETIC CORRELATIONS BETWEEN THE TRAITS I N CZECH PIED AND HOLSTEIN BULLS

A methodological procedure has been devised to calculate genetic corre lations on the basis of breeding values. The procedure takes into acco unt the fact whether breeding values were determined from the bulls pe rformance or from progeny performance, and whether the particular pair s of traits were measured on identical or different animals. Genetic c orrelations were determined between the traits available from milk rec ording in the reproduction field - fertility of bulls determined on he ifers and cows and fertility of daughters-heifers and daughters-cows; milk yield - milk quantity, fat quantity and content, protein quantity and content, and fat and protein quantity and content, and from meat performance - average live weight at 500 days of age and at slaughter, adjusted net weight gain, net weight gain, average daily gain from bi rth to 500 days, from 150 to 500 days, from birth to slaughter, yield grade and kidney fat proportion. Genetic correlations were calculated on the basis of correlations between relative breeding values of bulls for the particular commercial traits. Correlations between breeding v alues were calculated as residual using a GLM (SAS) procedure while th e effect of years of bull birth and groups of bull testing were taken into account. To determine the correlations between relative breeding values, data files were used covering 4,006 sires of Czech Pied cattle and 950 sires of Holstein cattle. High values of genetic correlations were estimated between the traits of milk performance - quantities an d contents of milk components and between the traits of meat performan ce - average live weight and average daily gains. Correlations between the groups of commercial traits in the field of reproduction, milk an d meat performance have only very low, maximally low positive and nega tive values. Medium-high values of correlations were determined betwee n some traits of milk and meal performance in Holstein cattle.