SOME ASPECTS OF INBREEDING AND ITS EFFECT ON GROWTH TRAITS OF LAMBS –A REVIEW

Abstract

Inbreeding seems to be a useful tool to improve the population by increasing the frequency of desirable genes, but the first result of inbreeding is inbreeding depression. Inbreeding depression implies the reduction of additive genetic variance and phenotypic values for efficiency traits in inbred animals. The kinship degree is measured by the inbreeding coefficient and expressed in percentage (%) from 0 to 100, that as the percentage higher, the higher the kinship. Nevertheless, one thing is for sure, practice in sheep breeding has shown that the use of inbreeding causes undesirable consequences like reduction of body shape or abnormal development, developmental delay, resistance to external influences and diseases, poor fertility or infertility, metabolic disorders, negative characteristics in fattening, albinism and the appearance of degenerative traits, loss of instinct, psychophysical defects and so on. Inbreeding is an inevitable companion of livestock production. No matter how hard we try to avoid it, in practice, it is almost impossible. It could not completely eliminate, but with proper breeding and selection management, it can be kept under control.