CORRELATIVE VARIABILITY OF SELECTIVE TRAITS OF RED DAIRY CATTLE
Authors: Polupan Yu. P. , Melnik Yu. F. , Bazyshyna I. V. , Pochukalin A. Ye. , Pryima S. V. 
Published: January 2022

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 < 0,001) and the inverse with the coefficient of reproductive ability -0,14… -0,34 for P < 0.001) confirms the presence of natural antagonism between milk productivity and reproductive function of cows. A significant (r = 0.29…0.48 for P < 0.001) level of age recurrence of milk productivity for the first three lactations was established.
The milk yield and milk fat of first heifers are positively and reliably correlated (r = 0.12… 0.19 by P < 0.001) with height at withers and rump, length of trunk and rump, width of biiliac, width of biischiatic and perimeter of the thorax. With the height and width of the chest, this relationship was low and unreliable, and with the perimeter of the shin – low, reverse and unreliable. The fat content in milk shows a significant (P < 0.01…0.001) direct relationship (r = 0.09…0.17) with the width of biischiatic, perimeter of the shin and length of rump and reliable (P < 0.001 ) inverse (r = -0,12…-0,17) with the height and width of the chest in the practical absence of correlation with the rest of the measurements.
The relationship between the estimated linear evaluation and the milk productivity of the first heifers was low, unreliable, and divergent in five of the ten descriptive features.
Conclusions. Milk productivity of first heifers of Red dairy cattle is directly proportional by Holstein conditional blood (r = 0.22…0.29) and inversely proportional (r = -0.15…-0.17) to Angler breeds.
Positive for the breeding improvement of the herd is the established inverse correlation (r = -0.10…-0.18, P < 0.001) by milk yield the first heifers with the age of the first calving. The detected antagonism (r = -0.14…-0.34, P < 0.001) between milk productivity and reproductive function makes it impossible to simultaneously select for milk and fertility.
The established reliable, statistically significant level (P < 0.05…0.001) of the relative variability of individual features of the exterior by different methods of its evaluation with the milk productivity of first heifers confirms the possibility and feasibility of indirect selection of cows of the desired type of exterior.
The established noticeable (r = 0.29…0.48 for p < 0.001) level of age recurrence of milk productivity for the first three lactations gives grounds to expect sufficient efficiency of mass selection of first heifers by their own productivity.