Effect of genotype, station and year of birth was studied on the population of 5408 yearling bulls bom in the period 1972 - 1987 and reared in 4 performance testing stations. Selection intensity of bulls and selection differentials in respect to body weight, height at withers and.heart girth varied between stations. In the period 1983 - 1987 selection parameters were slightly lower when compared with the period 1972 - 1981 Great preferences in selection were given to the crossbred bulls. In Polish black-and-white x HF and Polish black-and-white x British Friesian crosses selection parameters were lower than in pure Polish black-and-white bulls.
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