The effect of genetic and non-genetic factors on production traits of Simmental cows

This study covered 737 controlled first calving Simmental cows with, lactations concluded within one year. All first calving animals were on the farms of individual farmers in the municipalities of Kragujevac and Mladenovac. The research included the influence of bull sires, year and season of calving on milk yield and fertility. Least squares method was used to determine the average duration of lactation of 323.74 days. For a period of 305 days, heifers produced 3701.67 kg of milk, or 3644.58 kg of 4% FCM. The average production of milk fat was 144.26 kg and milk fat content was 3.88%. The interval from calving to first insemination lasted in average 124.19 days, and the animals were first calved at the age of 789.95 days. The bull sires had a highly significant effect (P0.05) of bull sires. Year of calving had a significant effect (P0.05). Season of calving of cows demonstrated highly significant effect (P0.05) on the production of milk fat, however it had no effect (P>0.05) on the milk fat content, duration of lactation and service period and age at calving