Analysis of breeding value in genomically evaluated German bulls-sires

This article presents a detailed comparative analysis of key breeding indices (RZG, RZM, RZE, Mkg, F%, E%) that determine productive properties of Holstein bulls. An ANOVA was conducted to assess the influence of age on these index values. The Fisher's criterion revealed significant differences between groups: for the overall breeding value index (RZG), it amounted to 144.5, and for exterior quality index (RZE) it reached 18.5 (both with p=0.0005). To investigate correlations among different parameters, pairwise correlation analysis was employed. Correlation coefficients were as follows: there was a positive relationship between general breeding index (RZG) and animal age (+0.672), strong direct dependence between fat content (F%) and protein level (E%) (+0.765), while milk yield volume (Mkg) showed negative association with protein concentration (E%) (-0.800). All mentioned correlations had high significance at p<0.01. Additionally, mean values of studied indices across various age groups were compared. Significant differences were found between young animals in their first year and mature individuals in their third year: general breeding index (RZG) differed by 16.1 points, exterior quality index (RZE) varied by 6.1 units (with both being highly significant at p=0.0005). Furthermore, statistically significant changes were observed from second to third years of life: total breeding merit (RZG) increased by 12.21 points (p=0.0005), productivity efficiency (RZM) rose by 1.98 points (p=0.049), exterior quality (RZE) improved by 3.51 units (p=0.001), and daily milk yield (Mkg) grew by 2.05 kg (p=0.042).