Phenotypic manifestation of signs of dairy productivity of cows of the Ukrainian black-and-motley dairy breed, depending on breeding indices of their ancestors

Goal. Using the example of cows of the Ukrainian black-and-white dairy breed, study the variability of signs of dairy productivity of animals depending on the values of the breeding indices of maternal and paternal ancestors. Methods. Signs of dairy productivity of controlled cows (n=714) were determined by the method of retrospective analysis of zootechnical accounting data for 2011–2020, taking into account the breeding indices of maternal (mothers, mothers of mothers, and mothers of fathers), and paternal ancestors (fathers, fathers of mothers, and fathers of fathers). The selection indices of the ancestors were established using the “Intesel Orsek” dairy cattle breeding management system and the catalogs of breeding bulls. The dependencies of signs of milk productivity of cows from breeding indices of their ancestors were determined using the tools of the software package Statistica 6.1, and based on maximum and minimum values of studied signs classes (gradations) of animals were calculated. The strength of ancestral influence on milk yield variability and fat content in milk was determined using univariate analysis of variance and Statistica 6.1 software package. The study results were processed using mathematical statistics and biometrics using Microsoft Excel 2010 software. The degree of intergroup differentiation was evaluated by comparing the arithmetic averages of each test feature. The reliability (probability) of the difference between group averages was determined by Student’s reliability criterion. Results. It was established that animals in the pedigree of which mothers, mothers of mothers, mothers of fathers, fathers, fathers of mothers and fathers had positive values of breeding indices gave higher yield compared to individuals with negative breeding indices of these categories of ancestors, but the fat content in milk in them was lower, which was explained by the antagonistic nature of these signs. For the formation of highly productive herds of dairy cattle of the Ukrainian black-and-motley dairy breed, animals should be selected by following indices: the breeding indices of mothers and mothers exceed the value of 2000, mothers of fathers are no more than 2000, fathers and fathers of fathers are more than 400, and fathers of mothers are 0–400. Conclusions. The formation of signs of dairy productivity of cows was significantly influenced by the breeding indices of maternal and paternal ancestors; however, the mothers of fathers and fathers, as well as fathers, had the most significant influence on them.