The genetics of colour in fat-tailed sheep: a review

Abstract

Fat-tailed sheep come in various colours-most are either brown (tan) or black. In some, most of the body is white with the tan or black colour restricted to the front portion of the body or to just around the eyes, muzzle and parts of the legs. The Karakul breed is important for the production of lamb skins of various colours for the fashion industry. As well as the black and tan colours there are Karakuls bred for grey or roan shades, a white colour or one of the numerous Sur shades. In the Sur shades, the base of the birthcoat fibre is one of a number of dark shades and the tip a lighter or white shade. All these colours and many others are the result of the interaction of various genes that determine the specifics of the coat colour of the sheep. A number of sets of nomenclature and symbols have been used to represent the various loci and their alleles that are involved. In the 1980s and 1990s, a standardised set, based closely on those of the mouse and other species was developed. Using this as the framework, the alleles of the Extension, Agouti, Brown, Spotting, Pigmented Head and Roan loci are described using fat-tailed sheep (mainly Damara, Karakul and Persian) as examples. Further discussion includes other types of "white markings," the Ticking locus and the Sur loci.

Identification of the e allele at the Extension locus (MC1R) in Brazilian Creole sheep and its role in wool color variation

“…Allele E D , which was subsequently characterized at the molecular level (Våge et al, 1999), is directly involved in sheep pigmentation (Lundie, 2004). Our data indicated that this allele is also clearly responsible for the wool color variation in Creole sheep, particularly determining the black phenotypes.…”

Corriedale Naturalmente Colorido – Histórico, características raciais e a origem das cores

“…Existem dois tipos principais de melaninas, a eumelanina (pigmento preto ou marrom) responsável por animais de fenótipo entre marrom e preto, e a feomelanina (pigmento vermelho ou amarelo) a qual resulta em lãs com tons avermelhados, bronzeados ou fulvos (Lundie, 2011). A essência das variações de coloração da pelagem da ovelha doméstica (Ovis aries) e os padrões destas, decorrem das quantidades e proporções de melaninas produzidos nas células dos folículos de lã e transportados para a pele e os fios de lã e/ou cabelo (Cockett;Shay & Smit, 2001;Deng et al, 2009).…”

Modificación Diluída de Colores en Ovinos Shetland y Ouessant

“…The study of color is an important part of the morphological characterization of domestic animals, which is in turn a very important aspect of livestock breed conservation (Alderson, 2018). Sheep color varies widely, although breeders targeting wools for industry have focused on white wool and have penalized colored fleeces (Adalsteinsson 1970, Sponenberg, 1997, Lundie 2011. Selection for whiteness has decreased the frequency of alleles that produce color, although these persist in many breeds as recessive variants.…”

“…Production of colored wool persists and provides value to those breeders involved. Previous studies have documented various alleles at the highly variable Agouti Signaling Protein locus, Melanocortin 1 receptor locus, and Tyrosinase Related Protein 1 locus (Adalsteinsson, 1970;Lundie, 2004, Lundie 2011, Sponenberg 1997.…”