Goncharenko I. The system of selection of dairy cows by the complex of traits

The purpose of this thesis is to study the system of dairy cows selection of Holstein, Ukrainian Red-and-White and Ukrainian Black-and-White dairy breeds, by the complex of traits during ontogenesis accounting for the length of embryogenesis; pedigree evaluation and detecting among the ancestors the presence of carriers of defective genes with recessive mode of inheritance, such as BLAD, DUMPS, МF etc; genetic markers (blood factors); reproductive ability; milk quality (fat and protein content); cows' longevity; resistance to mastitis (somatic cell number per 1cm3 milk); heritability coefficients (h2), correlations and regressions. The selection index for cows' systematic evaluation was calculated, according to the special formula and was proposed for the use as an integral selection trait. The theoretical approach to animal selection has been extended on the basis of regulations of ovogenesis and spermatogenesis. Theoretical assumptions have been formulated which postulate less variability of inheritance in females as compared to males. According to Interbull's requirements the method for evaluating sires, by the quality of their offspring, has been improved. The impact of sires on their daughters' longevity and reproduction ability has been proved. The possibility of a combination of high milk performance with a good reproductive ability and longevity has been proved in outstanding cows. The mathematical approach to family estimation within the breed has been developed. The possibility of milk yield prediction, with the use of genetic markers (blood factors) has been discovered. Scientific hypothesis on prognostic importance of blood factors, as genetic markers of QTL has been formulated. The system of cows' selection, which improves selection effectiveness of prospective dams of sires has been theoretically shown and practically realized. The application of this proposed step-by-step selection system has increased the selection effectiveness of cows in breeding and dairy herds by 20 - 25%. This has resulted in additional profits of 197.3 - 260 UAH per cow according to the prices in 2005.