ESTIMATION OF GENETIC PARAMETERS AND GENETIC TREND OF HOLSTEIN FRIESIAN CATTLE POPULATION IN TURKEY
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In this study, 194408 lactation and reproductive records of Holstein Friesian dairy cattle for the period of 1992-2012, which were taken from 23752 farms of Cattle Breeders Association of Turkey located in 10 cities, were evaluated. Variance components, breeding values, heritability, and repeatability of 305-day milk yield (305 DMY), lactation length (LL), dry period (DP), and calving interval (CI) were calculated by using MTDFREML. The effects of the factors (year of birth, lactation number, calving month, location, and calving age) that were thought to affect those traits (305 DMY, LL, DP, and CI) were evaluated. The heritability of 305 DMY, LL, DP, and CI was estimated as 0.22; 0.01; 0.01; and <0.01 respectively. Genetic trend for 305 DMY was also estimated as 7.44 kg/year. The estimated breeding values showed irregular fluctuations, but also the genetic trend increased in recent years. As a result, the estimated variance components, genetic parameters and breeding values could be used as selection criteria to increase the success of the selection in breeding studies for Holstein cattle population in Turkey.