Highland Cattle Coat Colour Genetics Explained

Highland Cattle Hair Colours

There are seven recognized Highland cattle hair colors:

• Red, Black, Brindle, Dun, Silver dun, Yellow and White

Originally, Highland cattle came in only two colors:

• Red

• Black

Through breeding, scientists later identified a dilution gene that alters these base colors.

The Dilution Gene

The dilution gene affects how strong the red or black pigment appears.

With one dilution gene

• Red → Yellow

• Black → Dun

With two dilution genes

• Red → White

• Black → Silver Dun

Silver dun cattle typically have:

• Grey pigment on the nose

• Black pigment on hooves

• Black pigment on horn tips

Genetic Rules

Some color combinations cannot produce certain offspring colors:

• Two red parents cannot produce dun or silver dun calves

• White or yellow parents cannot produce dun or silver dun calves

Other tendencies include:

• Brindle parents have a higher chance of producing black offspring

• Red Highlands often have small black hairs around the face, neck, and legs, which is necessary for brindle patterning

Coat Color Changes as Calves Grow

Highland calves often change color as they mature. Some Highlands may also show highlights in their coat. These highlights can appear on the tail, along the backline, in the dossan, or scattered throughout the coat

Common examples:

• Black and dun calves are often born chocolate brown

• Their true color becomes visible around 8–12 months

• The muzzle pigment is often the best indicator of their final color

Other changes:

• Red and yellow calves can look very similar at birth

• White and yellow calves can be difficult to distinguish when they are newborn

Coat Hair Colour Charts for Highland Cattle

What colour Highland calves to expect? With Homozygous Black (Eᴰ/Eᴰ)†

What colour Highland calves to expect? With Heterozygous Black (Eᴰ/x)*

Homozygous vs Heterozygous

The terms homozygous and heterozygous describe the two alleles (gene versions) an animal has at a specific gene locus. Every animal receives one allele from the sire and one from the dam

Homozygous

Homozygous = same gene twice

Examples in Highland colour genetics:

• e / e → red coat

• DH / DH → double dilution (white or silver dun)

• + / + → no dilution

Because both alleles are identical, the animal will always pass that same gene to its calves.

Example:

• A white Highland (DH/DH) will always pass a DH dilution gene.

Heterozygous

Heterozygous = two different genes

Examples:

• ED / e → black (because black is dominant)

• DH / + → single dilution (yellow or dun)

These animals can pass either allele to their offspring.

Example:

• A yellow Highland (DH/+) could pass:

  • DH → dilution

  • + → no dilution

So the calf colour becomes less predictable.

Chromosomes and Genes in Cattle

All cattle have 30 pairs of chromosomes (60 total).
These chromosomes are long strands of DNA that contain thousands of positions called loci (singular: locus).

Each locus contains genes that control specific traits, such as:

• Coat colour

• Horn shape

• Temperament

• Growth

• Meat marbling

Most genes are the same in all cattle breeds, because they control basic features that make cattle different from other animals.
However, a small number of genes differ, and these differences create variation between breeds and individuals.

Coat Colour Genetics

Coat colour in cattle is not controlled by just one gene.

Instead, there are six major colour loci that interact to determine the final coat colour. There are also several minor loci that can modify the appearance.

These six major loci are believed to exist in most mammals, which is why similar colour genetics appear across many species.

Each locus can contain different versions of a gene, called alleles.

Different combinations of these alleles produce the wide range of colours seen in Highland cattle.

Because multiple loci interact, coat colour genetics becomes complex and sometimes difficult to predict.

What Is “Wild Type” Colour?

The term wild type refers to the original or default colour pattern found in wild ancestors.

For cattle, the wild type colour is believed to be similar to the colouring of the ancient European aurochs, the ancestor of many British cattle breeds.

This colour was roughly:

• Red-brown body

• Darker shading in some areas

Many other coat colour genes are dominant over this wild type base colour.

Genetic Naming System

Geneticists use a standard system to describe colour genes.

1. Locus Names

Each locus has a letter representing it.

Example:

• D locus = dilution gene

2. Allele Symbols

Alleles are written using the locus letter plus a symbol.

Example at the E locus (Extension locus):

Eᴰ = Black colour gene
E⁺ =Wild type colouring
e = Red colour gene

3. Dominant vs Recessive

• Capital letters = dominant genes

• Lowercase letters = recessive genes

Example:

• Eᴰ (dominant black)

• e (recessive red)

4. Two Alleles Per Locus

Each animal inherits two alleles at every locus, one from each parent.

They are written with a slash between them.

Examples:

• Eᴰ / Eᴰ → black

• Eᴰ / e → black (dominant)

• e / e → red

Why Highland Colour Genetics Is Complex

Colour in Highlands depends on interactions between several loci, including:

• E locus – controls black vs red pigment

• D locus – dilution (yellow, dun, white, silver dun)

• A locus – brindle pattern (when E+/e or E+/E+)

• Other modifier loci

Because of these interactions:

• Some colours cannot appear in certain parents

• Some calves change colour as they grow

• Some genes remain hidden for generations

Highland Coat Colour Oddities

Although there are eight officially registerable Highland colours in the UK Herd Book, some animals show unusual colour patterns that fall outside the normal categories. These likely reflect the wide genetic diversity in the breed’s early history.

These traits add interest to breeding Highlands but also make coat-colour genetics more complex.

Mahogany (“Frosting”)

Mahogany is a dark red coat colour with distinctive white-tipped hairs. Most noticeable, especially on the dossan, tip of the tail and variable amounts along the topline and mane. Very striking in young calves, but the contrast usually fades as the animal matures. Some breeders also call it “frosting” because of the frosted hair tips.

Bus Dubh (Black Muzzle Ring)

Bus Dubh is a traditional Highland trait where the animal has a ring of short black hairs around the muzzle.

Characteristics

• Only appears in red Highland cattle

• Forms a dark ring around the nose

• Intensity can vary:

  • between seasons

  • between years

Interesting points

• Seen more often in cows than bulls

• Some breeders believe it may be linked to the brindle gene

• It is often considered a historic Highland characteristic, rarely seen in other cattle breeds

The name Bus Dubh comes from Gaelic, meaning “black muzzle.”

Parti Colour

Parti colour is a fairly rare pattern where a Highland has white patches combined with a solid colour (usually red or yellow).

Possible genetic origin

Research into pedigrees suggested many parti-coloured animals traced back to two ancestors: a bull, Sgaithanach, and a cow, Rosie (around 1870) This suggests the trait may follow a simple recessive inheritance pattern, since it can appear unexpectedly from carrier parents.

White Udders

A white udder in Highland cattle is a common marking where white hair or skin appears on the udder and sometimes extends toward the navel, is acceptable within breed standards if it does not go past the navel, occurs in up to about 50% of herds, and is thought to be caused by a gene related to white spotting, possibly linked to the same locus as the parti-colour gene. 🐂🧬