23/08/2026
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The red, white & roans of the Shorthorn Breed always make calving time a bit like taking a pick from the box of favourites, however there is a science behind it.
The red gene is the recessive gene of the red/black coat colour locus, with Shorthorns expressing a red coat by carrying 2 alleles of the red gene. The recessive nature of the red gene is also the reason why a solid red shorthorn crossed with a Homozygous Black coated animal will result in a solid black or black based blue roan calf.
The roan or white expression in a calf is controlled separately at the Roan Locus. The roan locus consists of a Dominant & Recessive roan allele, an animal that carries 2 of the dominant roan alleles will express a pure white coat, comparatively the animal carrying 2 copies of the recessive gene will express a red coat when combined with the dual recessive allele of the Red/Black Locus.
The expression of a roan coat is caused by the codominant heterozygous expression of both the dominant & recessive alleles at the roan locus. However the level of expression of roan throughout the coat will vary significantly from a few white hairs to an almost completely white calf, all from the same genotype.
The roan genotype is what gives us the lucky draw at calving time, with the cross of 2 roan expressing animals giving a 25% chance of a Red calf, a 25% chance of a White calf & a 50% chance of a roan calf.
To put it simply, the red gene determines the base pigmentation of the animal & the combination of dominant & recessive alleles in the roan locus determines the distribution of the pigmentation on the coat.
