Comparative analysis of the results of the breeding assessment of Holstein young sires of German origin, depending on age

The purpose of practical breeding work in dairy cattle breeding is to evaluate and select animals that are outstanding in hereditary qualities, however, direct selection for a number of quantitative characteristics requires high costs, effort and time, especially when selecting for several characteristics at once. Breeding using the index evaluation of animals is able to solve this problem and significantly increase the effectiveness of breeding work. The purpose of the presented article was to compare the breeding indices (RZG, RZM, RZE, RZS) of Holstein gobies of German breeding depending on age. Statistical processing of the herd bonus results allowed us to establish that the average values of the index of the total breeding value of steers were 136.97 ± 0.412 and 134.9 ± 0.256 for 2023 and 2022, respectively, with a bilateral significance equal to 0.0005. The most significant correlations between the indices were obtained for RZG and RZM at the level of 0.51 (p