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The aim of the research. In breeding practice, it is important to select and take into account genetically and physiologically determined patterns of age recurrence and relative variability (correlation) between different economically useful traits in the process of ontogenetic development of animals. This opens up opportunities to increase the efficiency of selection through the use of early selection (forecasting) on indirect grounds. The aim of our research was to identify and analyze the relative variability of selected traits of dairy cattle in the herd of a leading breeding farm for breeding of the Ukrainian red dairy breed. Materials and methods of research. The study was conducted on the basis of primary breeding records in the herd of one of the leading breeding farm for the breeding of the Ukrainian Red dairy cattle in the LLC "Russia" of Donetsk region. The materials of the electronic information database in the format of the Dairy Management System “ORSEK” were used. To substantiate the accounting period, the average milk yield of the first heifers of the herd was calculated according to the years of the first calving. Significant differences in animal productivity in the chronology from 2005 to 2015 of calving were established. Controlled cows were evaluated by the age of the first calving, the coefficient of reproductive ability and milk productivity and live weight for the first three lactations. A total of 1061 first heifers were evaluated on the exterior during the control period. Regularities of relative variability established in the herd were studied by correlation analysis of milk productivity of first heifers with productivity for subsequent lactations (age repeatability), measurements, linear descriptive features and body structure indices. Research results. Correlation analysis was established a different level and direction of the relationship between the indicators of milk productivity of first heifers with some of the studied traits. First of all, it is worth emphasizing the relatively higher and highly reliable relationship of all studied indicators of milk productivity of first heifers with conditional blood by improving breeds. In the studied breeding herd, the natural antagonism between the main selected signs of milk yield and fat content in milk was overcome. The correlation between these features was quite noticeable, direct and reliable at a higher degree of statistical significance. It is considered positive for the selective improvement of the herd, although the low but highly reliable inverse correlation of the milk yield of the first heifers with the age of the first calving is established. The average age of calving of the studied first heifers was quite late – 965 ± 3,0 days or 31,7 months. The average daily gains of live weight of heifers up to a year was 630 ± 2,5 g, at the age of 12–18 months – 549 ± 2,6 g. The first calving at the age of two (24 months) is currently considered optimal for the Holstein breed. The intensity of growing heifers up to a year is desirable at the level of 750–800 g per day, in 12–18 months – 650 g. Significant direct relationship between milk yield, milk fat content and yield for 305 days of lactation of first heifers with the duration of the period between the first and second calving (0.12… 0.30 at P |
