Effect of systematic factors on milk Production per milking, productive and lifetime day in Simmental cows

Abstract

One of the very important functional characteristics of dairy cows is milk production per milking, productive and lifetime day. Due to the pronounced action of both genetic and paragenetic factors, the phenotypic expression of this trait is characterized by high variability.The effect of fixed (breeding area - farm, season and year of birth, total number of lactations) and continuous (age of cows at first insemination) paragenetic factors was carried out on a sample of 2 548 Simmental cows distributed in three breeding areas: Zlatiborski Suvati farms with free-stall housing system (n=502), farms in Dobrichevo with a tie-stall housing (n=956) and individual tie-stall in the area of the Agricultural Cooperat from Kotraža (n=1090).Based on the statistical analysis using the GLM procedure, it was determined that the general average for milk production per milking, productive and lifetime day was 12.79 kg, 9.31 kg and 5.47 kg, respectively.Breeding area, year of birth and total number of lactations significantly influenced (P<0.01) the phenotypic expression of all the traits. Season of birth did not significantly affect any of the observed functional traits (P>0.05), while age at first insemination as a continuous factor significantly affected milk production per milking day (P<0.05) and especially milk production per productive and lifetime day (P<0.01).