Characteristics of the productive-economic indicators of cows of Yaroslavl breed of different genotypes

Abstract

Abstract. Aim. The study of the influence of crossbriding on the growth and development of heifers and subsequent productive and reproductive qualities of cows on the first lactation. Methods. Using statistical methods, correlation analysis and ANOVA for evaluated genetic indicators of economic-valuable traits of dairy cattle. In particular was studied live weight of heifers from birth to 18 months, first insemination age and first fecundation age, live weight at fecundation, frequency of insemination, first calving age, days open, live weight at first lactation, milk yield for 305 days (kg), fat (%, kg) and protein (%, kg) in milk. Results. Relationship between productive indicators and the genotype of the animal is established. When assessing the strength of the influence of the factor «blood on the Holstein breed» it was found that the greatest impact can be traced at the age of 6 and 18 months, and is respectively 12.7 % and 17.1 %.The reproductive qualities of the first-calf cows decreased with the increase percent of blood in the Holstein breed. Evaluation of the impact of crossbreeding on milk production at first lactation has revealed significant strong influence on milk yield for 305 days of first lactation, and related signs the amount of milk fat and protein. According to qualitative indicators, the low influence of the Holstein blood fraction was found, while to a greater extent on the fat content than on the protein content in milk. Evaluation of phenotypic and genotypic correlations of milk yield and quality components of milk revealed average negative phenotypic and low negative genotypic correlation in all groups. The exception was in heifers of Yaroslavl breed with percent of Holstein blood less than 50 %, in which the relationship of yield x protein was positive. The relationship between milk yield and fat and protein content in milk has the opposite moderate character and strength. Practical significance. Studies was established that breeding of animals of Holstein and Yaroslavl breeds in one herd allows to receive an optimum ratio of milk production with optimal percentage fat and protein. For this herd among animals of the improved genotypes of the Yaroslavl breed, the use of genotypes with a percent of blood in the Holstein breed from 75.1 % to 87.6 % is optimal, which should be taken into account when selecting bulls to the breeding program.