EVALUATION OF GENOTYPE OF BREEDING BULLS BY PROGENY QUALITY

By examining the genealogical structure of the herd, lines with ancestors obtained through intra-line breeding were carefully chosen. The daughters of VISION-GEN MAURY-ET bull demonstrated the highest milk yield for 305 days of lactation, producing 7177.5 kg, which was 106.4 kg more than the average for all bulls. The daughters of HAMMER-CREEK OB KEYBOARD-ET excelled in protein-milk yield, surpassing other bulls by 0.44% and the breed standard by 0.54%. VISION-GEN MAURY-ET proved to be a significant milk yield improver, while LOCKER-LANE RW BANNING'S daughters excelled in fat-milking and HAMMER-CREEK OB KEYBOARD-ET's daughters were known for their protein-milking improvements. Studies have revealed that cows of the REFLECTION SOVEREIGN line demonstrated the highest milk production, yielding an average of 7409 kg of milk with a fat content of 3.62% and a protein content of 3.22%, while maintaining an average weight of 547 kg. The research also showed that as the live weight of cows increased, so did their milk yield, with a peak yield of 7774.8 kg achieved by cows weighing 562 kg in the REFLECTION SOVEREIGN line, surpassing their WIS BURKE IDEAL counterparts by 221.4 kg. Furthermore, the milk ratio of cows increased with their live weight, and the milk content coefficient of cows from the REFLECTION SOVEREIGN line was 1383.4 kg, exceeding that of the WIS BURKE IDEAL line by 2.6 kg.