HOLSTEINIZATION OF OPEN REGIONAL POPULATION OF BLACK-AND-WHITE CATTLE AND PROSPECTS OF ITS FURTHER IMPROVEMENT
Analysis of breed formation process in the population of black-and-white dairy cattle of the Northern Polissya region has been carried out. Breed and genealogical structure of the female stock on the five basic breeding farms has been studied. The main factors of breed forming process which lasted sixty years have been determined. They are: use of the gene pool of the nine related breeds of black-and-white root (Ost-Friesian, Dutch, Estonian, Russian, Ukrainian, Holstein, Swedish, Danish, German), transfer to entire use of sires and lines of Holstein breed of North American selection, gradual increase of sires pedigree value and genetic advantages of the lines, used in breed formation. Four periods of breed formation have been marked out. They are: I (1945-1960 years) - dominating breed Ostfriesian, II (1961-1980) - Dutch, III (1981-1990) -Dutch and Holstein, IV (1991-2010) - Holstein. 110 sires of different breeds of black-and-white root and 25 lines have been evaluated. It has been discovered that the process of female livestock Holsteinization, which lasted 30 years on the base farms, resulted in an increase of weight and line parameters of the first-calf cows, change of their exterior and constitutional type tending to the narrowing of body, significant increase of milk yield and fat in milk, but decrease of their reproductive ability. Holstein sires excel the sires of local selection in productivity of their nearest female ancestors, daughters’ phenotype indices and indices of pedigree value, which testifies to the expediency of their further use. To avoid «genotype-environment» contradiction the system evaluation of cattle in populations by the principal productive traits and degree of realization of their genetic potential is recommended. An improved method of assessing a group of cows on a range of characteristics providing a comparison of the parameters of animals with the parameters of the desired type.