The dissertation research provides the dynamics and peculiarities of the formation of productive and functional parameters of horses of the Novoolexandrivskii draft breed in the process of its improvement in retrospect and the current state of the breed are studied, the factors influencing the mares' milk production are determined. It was found that the mares of the Dibrivskii Stud have a high potential for the development of productive horse breeding in Ukraine.
The current state of the Novoolexandrivskii draft breed, features of the breeding populations, linear structure, and external characteristics of horses were studied. It has been found that the current composition of the Novoolexandrivskii draft breed is limited to 301 horses, including 176 mares of reproductive age. In the reproduction, 17 stallions of the genealogical lines Tantal’s (55.6 %), Gradus (22.2 %), Koketlivii (16.7 %) and Borets (5.6 %) are used. It has been established that linear affiliation affects the external characteristics of horses, mares' milk production and polymorphic blood systems.
Indicators of milk production and milk quality of mares of the Novoolexandrivskii draft breed were determined, the influence of mare age (lactation number), lactation period, foaling duration, foal sex, and mare lineage on these indicators was established. Correlations between mares' milk quality indicators were established.
The relationship of body measurements, body structure indices and udder parameters of Novoolexandrivskii draft mares with their milk production was determined. A negative correlation of mares' milk production with withers height (r=-0.511; p˂0.05) and a positive low correlation with chest girth (r=-0.200; p˂0.05) were found. A higher positive level of correlation between milk yield and body structure indices was found (r=0.353-0.499). Determination of the dependence of milk production on udder parameters allowed to establish its positive relationship with a high degree of girth and length of the udder (r=0.632 and r=0.616, respectively), udder depth had a much lesser effect on milk production.
According to the data obtained, it is recommended to select massive mares with high indicators of chest girth, udder girth and length for the repair stock.
The intra-breed polymorphism of the breed according to the polymorphic systems of blood and proteins (Tf, Al and D-system of blood groups), the level of relatedness of the structural units of the breed, and the possibility of using marker-assisted selection to increase the milk production of mares were analysed. The dynamics of the immunogenetic profile of horses of the Novoolexandrivskii draft breed by periods of improvement was established. The branching of the Novoolexandrivskii draft breed in terms of both genealogical structure and immunogenetic profile was proved, which allows the selection process to be carried out without the threat of inbreeding depression.
The relationship between the milk production of Novoolexandrivskii draft mares and some alleles of the blood group D-system of blood groups, polymorphic systems of transferrin and albumin was established. The highest level of milk production was found in mares with genotypes Dde (0.6275) and Dcgm (0.3124), transferrin FF (0.0725), and albumin BB (0.0213). The overall low fat content in the milk of the studied mares was more associated with the genotypes Ddk (0.3124) and Dcgm (0.3124), transferrin DD, albumin AB.
The genetic markers of Novoolexandrivskii draft breed and Tori horses were analysed to determine the similarity and difference of genotypes. The high level of antigenic similarity for some alleles of the D-system of blood groups, transferrin and albumin between the breeds proves their genetic similarity, which can be further used to improve the technological characteristics of both breeds through partial crossbreeding. Recommendations for the use of genetic markers in the strategy of conservation and improvement of draft breeds were given.
The Breeding Programme for the Novoolexandrivskii draft breed until 2020 (extract from protocol No. 1 of 28.11.2014; Ministry of Agrarian Policy of Ukraine) and the Programme for the conservation of the horse gene pool in Ukraine until 2025 (protocol No. 4 of 11.11.2020; IT NAAS) were developed.
The identified patterns are the basis of the monograph: ‘Selection and Genetic Monitoring in Horse Breeding’ (section 4.6. Novoolexandrivskii draft breed) (ISBN 978-966-540-528-3).
