SELECTION ANALYSIS OF THE FORMATION OF THE REPRODUCTIVE COMPOSITION OF THE NEWLY CREATED UKRAINIAN TROUT BREED GROUP OF HORSES
Authors: Tkachova Iryna 
Published: May 2023

The object of research was an array of breeding mares of the newly created Ukrainian trotting breed group of horses, registered as of 01.01.2023 (n=194). 91.6% of all breeding mares were tested on racetracks with an average liveliness of 2.12.9 min. The quantitative and qualitative indicators of the investigated array, the genealogical structure, and the effectiveness of genealogical combinations were determined.
The liveliest mares were selected for breeding stock of the Dibrivskiy stud (average liveliness 2.08.2±0.86 min.). In prize-winning precocity, mares of Zaporizhskiy stud with a high probability (p<0.01) prevail over mares of other stud farms (average sprightliness at 2 years of age – 2.24.9±1.47 min.). The highest record liveliness at an older age in mares of the Dibrivskiy stud (2.05.4±0.64 min.). Of all the evaluated mares of the newly created breed group, 12% are in the liveliness class of 2.05 min. and more lively and almost half (48.8%) to class 2.10 min. and livelier. The majority of mares belong to the liveliness classes of 2.05.1-2.10.0 min. (36.8%), 2.10.1-2.15.0 min. (19.7%), 2.00.1-2.05 min. (12,0 %), 2.15.1-2.20 min (9.4%). In the breeding stock of the Dibrivskiy stud, 10 mares (32.3%) are in the liveliness class of 2.05 min. and more lively, 21 mares (67.7%) are to liveliness class 2.10 min and livelier. In general, it can be stated that liveliness is a fairly consolidated feature (Cv=7.28) of the reproductive composition of the newly formed trotting breed group.
According to the results of the assessment of body measurements, it was established that the mares of the Dibrivskiy stud prevail in terms of height at the withers and length of the body (p<0.05), so it can be stated that the selection strategy of this farm is aimed at the right movement of combining high prize productivity with exterior indicators. Mares of all stud farms practically do not differ in chest girth and wrist. the highest score for origin, type, exterior and prize performance was given to mares of the Dibrivskiy Stud (p<0.05). The mares of the Lymarivskiy stud farm received the highest marks for their measured performance.
The analysis of the genealogical structure determined the origin of breeding stallions from 6 and reproductive mares from 9 genealogical lines. The Speedy Crown line is the most developed in terms of stallions and mares (46.7 and 34.3%, respectively). The highest record liveliness for the distance of 1600 m (at the level of liveliness class 2.10 min. and livelier) belongs to mares of lines: Hut Moon (125.5±1.55 s) and Arnie Almahurs (127.6±1.37 s). The most precocious mares of the lines: Low Hanover (142.7±3.17 s), Worthy Boy (143.1±1.53 s), Hut Moon (144.5±3.75 s) and Speedy Crown (146.1±1.71 s). The studied array of mares is divided into 25 maternal families. The results of the analysis show that Ruta's mare of line is most effectively combined with genealogical lines.
Keywords: horses, Ukrainian trotting breed group, breeding mares, genealogical combinations, lines, parent families, generation, selection traits.