Genetic background of coat colour in sheep

The coat colour of animals is an extremely important trait that affects theirbehaviour and is decisive for survival in the natural environment. In farmanimal breeding, as a result of the selection of a certain coat colour type,animals are characterized by a much greater variety of coat types. This makesthem an appropriate model in research in this field. A very important aspectof the coat colour types of farm animals is distinguishing between breeds andvarieties based on this trait. Furthermore, for the sheep breeds which arekept for skins and wool, coat/skin colour is an important economic trait.Until now the study of coat colour inheritance in sheep proved the dominanceof white colour over pigmented/black coat or skin and of black over brown.Due to the current knowledge of the molecular basis of ovine coat colourinheritance, there is no molecular test to distinguish coat colour types insheep although some are available for other species, such as cattle, dogs,and horses. Understanding the genetic background of variation in one of themost important phenotypic traits in livestock would help to identify newgenes which have a great effect on the coat colour type. Considering thatcoat colour variation is a crucial trait for discriminating between breeds(including sheep), it is important to broaden our knowledge of the geneticbackground of pigmentation. The results may be used in the future todetermine the genetic pattern of a breed. Until now, identified candidategenes that have a significant impact on colour type in mammals mainly codefor factors located in melanocytes. The proposed candidate genes code for themelanocortin 1 receptor (MC1R), agouti signalingprotein (ASIP), tyrosinase-related protein 1 (TYRP1),microphthalmia-associated transcription factor MITF, and v-kitHardy–Zuckerman 4 feline sarcoma viral oncogene homologue (KIT).However, there is still no conclusive evidence of established polymorphismsfor specific coat colour types in sheep.