Black/red coat colour / Red factor and Telstar (MC1R) - Holstein

About MC1R and coat colour

The MC1R gene, also known as Extension or the E locus, plays a major role in black and red pigment production in cattle. In Holstein cattle, the classic red factor and the Black/Red Telstar factor are especially useful for breeding decisions.

The red factor is relevant for animals that can become red and white when they carry two copies of the recessive red allele. The Telstar factor, also known as Black/Red or E(BR), causes a distinctive pattern in which calves can be born red and later turn black, often within a few months. Other loci, including Dominant Red and white spotting, can still influence final visible coat colour.

Practical value of this test

• Red factor: shows whether an animal carries the recessive red allele.
• Telstar: helps identify Black/Red carriers in Holstein lines.
• Breeding planning: supports targeted matings for desired black/red coat colour outcomes.

The result helps breeders predict colour inheritance, identify carriers correctly and plan Holstein colour goals more deliberately.