THE PHENOTYPIC VARIABILITY OF PRODUCTION TRAITS IN THE POPULATION OF SIMMENTAL COWS

Abstract

The breeding objective for the Simmental breed of cattle is to achieve maximum genetic values for economically important traits, in line with the economic effects of genetic improvement, which this breed has achieved in developed countries. The present study included 302 Simmental cows selected as bull dams on the territory of the Republic of Serbia in the course of one year. The impacts of paragenetic factors and lactation on production traits (milk yield and fertility) were examined. Order of lactation influenced highly significant deviations (P<0.01) in milk yield, milk fat content, milk fat yield and 4% FCM from the general average, as well as slight variations in the length of gestation and lactation, calving interval and service period, that were not statistically significant (P>0.05). Simmental bull dams included in the present study, in the lactation period of 311.45 days, have realized milk yield of 5754.49 kg with 3.98% and 230.24 kg of milk fat and 5755.47 kg of 4% FCM. Average duration of gestation of tested heads was 286.31 days, the service period 110.37 days, and calving interval 398.44 days. Overall comprehension and understanding of a number of paragenetic factors and their interactions on specific production characteristics can have impact on improvement of milk yield and fertility in cows.