Production traits of Simmental bull dams in first lactation across different districts of Serbia

Milk yield and composition are among the most important traits in cattle production. The aim of this study was to analyse the production traits of Simmental bull dams in their first lactation in Serbia and to evaluate the influence of the district (breeding region) on the variability of these traits. The study included 408 Simmental cows selected as bull dams from eight districts: Kolubara, Podunavlje, Braničevo, Šumadija, Zaječar, Rasina, Nišava and Belgrade. Milk production traits in the first lactation were standardised to 305 days and included milk yield (kg), milk fat content (%), milk fat yield (kg), protein content (%) and protein yield (kg). The data were analysed using one-way analysis of variance (ANOVA) with the district as a fixed factor. The average milk yield in the first lactation was 6093 kg, with an average milk fat content of 4.00% and protein content of 3.25%, confirming that these cows represent a highly productive segment of the Simmental population in Serbia. Highly statistically significant differences (p < 0.001) were found between the districts for all analysed traits. The highest average milk yield was recorded in the Nišava district (6792 kg), the lowest in the Podunavlje district (5735 kg). The highest milk fat content (4.30%) and the highest milk fat yield (288.89 kg) were recorded in the Zaječar district, while the highest protein content (3.35%) was recorded in the Šumadija district. The results presented indicate the need to optimise selection criteria and improve rearing conditions in districts with lower production levels in order to support the sustainable development of milk production in Serbia.