ADAPTATION AND SELECTION OF HOLSTEIN COWS UNDER LONG-TERM RAISING

Abstract

The effect of the long-term selection process on adaptation of Holstein breed of cattle to specific natural-climatic conditions of Sakhalin was studied. The coefficient of selection was determined by assessing relative adaptabilities of genotypes through selection and preserved after being selected through relative adaptability. Studies have shown that the population of limited size had a low degree of adaptation to raising conditions, showed no heterosis and reduced flexibility in next generations. Productivity for 305 days of lactation under unfavorable conditions of feeding and keeping can be considered as a trait with the intermediate optimum, because the animals with the population averages have the highest degree of adaptation, and selection contributes to intermediate indices. The animals having average characteristics become more adapted as they possess the optimum values of traits. The adaptation degree depends on genetic variability of traits.