Correlation Analysis of Breeding Indices in Holstein Sire Bulls Depending on Age

This study presents a comparative analysis of the correlation relationships among breeding indices of Austrian sire bulls born in 2022, 2023, and 2024. It was found that the total breeding value index (RZG) consistently demonstrates a strong positive correlation with productivity (RZM) and utilization direction (RZN) indices across all groups (r = 0.514–0.584; p<0.001). A systematic negative correlation was observed between RZM and vitality (RZE), indicating a persistent selection tradeoff between productivity and robustness. The reproduction index (RZR) showed a stable positive relationship with RZN (r = 0.407–0.515; p<0.001), reflecting phenotypic integration of functional and conformation traits. The analysis revealed an overall stability in selection trends, with a slight increase in negative trait correlations in the 2024 cohort. These findings have practical implications for adapting foreign genetic material under Russian conditions and for optimizing breeding programs.