Stabilisers are red or black but sometimes other colours appear..........

Inheritance of coat colour is mostly reasonably straight forward but can get a bit confusing when cattle with white coats appear in the pedigree. So the first stage is fairly easy…..

In Stabiliser cattle the predominant coat colours are red or black. Black is dominant to red. So if we represent a copy of the black gene as B and the red gene as b the outcomes in the table below will follows

Table 1. Expression of Coat Colour
Sire Dam Calves
Homozygous black (BB) Homozygous black (BB) 100% Homozygous black (BB)
Homozygous black (BB) Heterozygous black (Bb) 50% Homozygous black (BB)
50% Heterozygous black (Bb)
Homozygous black (BB) Homozygous red (bb) 100% Heterozygous black (Bb)
Heterozygous black (Bb) Homozygous red (bb) 50% Heterozygous black (Bb)
50% Heterozygous black (Bb)
Heterozygous black (Bb) Heterozygous black (Bb) 25% Homozygous red (bb)
50% Heterozygous black (Bb)
25% Homozygous black (BB)

Unfortunately there is another gene active on this red/ black site and it’s known as a “wild type” which we could call B+. When B+ gets involved it seems to be neutral so B+ /B is black and B+ /b is red.

 

black red inherit
White effects.........

This is where it gets a bit more complicated.   So you have to remember that the genes controlling whiteness are in a different place from the red/ black site. All the red/ black stuff described above is still going on and the genes on the white site can override or modify whatever is happening at the black site.

Most Charolais are bb on the black/red site so you would expect them to be red when you look at these genes. But the whiteness gene site now comes into play and if it is homozygous WW this overrides whatever is on the black red site and means the cattle have a white coat.

In Highlands and Galloways there is a variant that produces a Dun colour on this white site and Dun is also dominant to black/red when it’s there as a homozygous Wd/Wd.

If you get a heterozygous animal on the white site Wd/wd then BB and Bb (black looking animals) will appear as various shades of grey/charcoal. Similarly red animals (bb) when paired with the heterozygote white may appear yellow

The white faces from Herefords and Simmentals are controlled separately from any of the gene sites mentioned above!! Evidence to date shows that the white face seems to be a dominant trait which means heterozygotes show the white face.

It might not look like it but Holsteins follow the red /black inheritance described right at the start but have the added extra of a white spotting gene and, on a completely different site, a red dominant gene.

white inherit
white inherit2
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