THE DEGREE OF PHENOTYPIC CONSOLIDATION OF DIFFERENT DAIRY CATTLE BREEDING GROUPS

Abstract

The value of various breeding groups of animals is determined not only by their level of productivity, reproduction, product quality, technological adaptability etc., but also by the level of phenotypic consolidation, which ensures the necessary homogeneity and a stable level of desirable traits. The purpose of the research was to study the phenotypic consolidation of various breeding groups of dairy cattle (half-siblings, lines, breeds).It was established that the most consolidated by milk yield, the fat and protein content in milk, the age at first calving and the calving interval are groups of half-siblings (К A5 = 0,202) compared to the phenotypic consolidation of lines (К A5 = 0,035) and breeds (K A5 = 0,088). The most consolidated according to the studied characteristics are the groups of daughters of the bulls Nirvana 101709244 (К A5 = 0,317) and Tahoe 8189401 (К A5 = 0,331), lines of cows and related groups – Marshall2290977 (К A5 = 0,193) and J. Besn 5694028588 (К A5 = 0,103 ), as well as the cattle of Ukrainian Black-and-White and Red-and-White dairy breeds (K A5 = 0,144 and K A5 = 0,129, respectively). It was determined that the level of phenotypic consolidation increases with decreasing of genetic variation of the traits. On average, higher consolidation was observed for traits with low genetic variation (fat and protein content in milk).For milk yield the level of phenotypic consolidation was much lower. For the first calving age and the interval between 1 and 2 calves, the studied groups of animals can be classified on average as unconsolidated. The most consolidated in five traits are the half-siblings cows (the lowest level of the systematic hierarchical structure), and the much lower consolidated are cows of different lines and breeds (higher levels in the systematic hierarchy). Therefore, as the level of the breeding group increases, the degree of their phenotypic consolidation in the breed hierarchy decreases.