STUDY ON THE SELECTION INTENSITY IN BLACK AND WHITE COWS

Abstract

A study was initiated to establish the intensity of selection in Black and White cows. It involved systematized and processed milk records of 484 adult (main herd) and 198 primiparous cows from three herds of different productivity: herd I - Agricultural Institute - Shumen with average milk yield >6500 kg; herd II - "Obraztsov Chiflik" farm, Russe, with >5500 kg; and herd III - Institute of Animal Sciences, Kostinbrod, with >4500 kg. The data were analyzed using the conventional statistical procedure. The results indicate that: The selection intensity for the trait milk yield in the studied Black and White cows has optimal values ranging from 0.69 to 0.85 among herds. The milk yield ranges from 4586.43 to 6831.16 kg in the pluriparous cows and from 4537.69 to 4635 kg in the primiparous. For the replacement in the main herds on all three farms have been used only productive generations.