Most of us have a good understanding of the two most common coat color alleles ~ the red and the black versions. Black is dominant to red so red cattle must have two red alleles and black cattle can either have two black alleles (homozygous) or can carry a red allele (heterozygous). Wild Type is a third option for the primary coat color gene (called the extension gene). The Wild Type allele is less common in our population of cattle and other genes can affect the coat color display. A Simmental homozygous for the Wild Type allele will likely be brownish red or brownish black with darker areas around the muzzle, ear tufts, and tail switches.
Added by Sally Buxkemper
The wild-type allele allows for the production of both red and black pigment. Many Simbrah and most Brahman have the wild type and also Brown Swiss, Tarantaise, and Jersey. A brindle also has a wild type allele. Many red breeds carry the brindle gene but it is not expressed unless the animal has a wild-type allele. Most European (fullblood) Simmentals do not carry the brindle gene. Red breeds like Hereford, Red Angus and some red Simmentals may also carry the brindle gene but it is not expressed unless combined with a wild-type. Some Red Angus and Red Simmentals have one copy of the wild-type Extension. They often have a black nose.