Myostatin (NT821) is a recessive gene that influences the development of muscle. Cattle can carry the recessive gene without any ill effect, but if it carries to copies off the recessive gene the cattle will express the characteristics known as double muscling. These cattle can not be registered. Breeding with intention to the genetic profile of each animal means breeders can readily avoid breeding cattle with this combination of recessive myostatin genes.

Some Speckle Park cattle carry the recessive gene for red coat colour. If they carry one copy of the gene the black colour will dominate and the cattle will appear as black. These cattle can be registered. Cattle carrying two copies of the red gene will have a red coat colour. These cattle can not be registered, although they may be excellent cattle. Checking the red gene status of the cattle you are going to breed in the registry will allow you to avoid breeding calves which express the red colour.

Speckle Park must be polled to be registered. Like the genes of the red colour and myostatin, the gene for horns is recessive. The register will tell you if the cattle you are looking for is polled and it will tell you whether the cattle carries the recessive horned gene too. Homozygous polled means they don’t carry the horned gene but attention to the status of the cattle you are breeding to will allow you to avoid producing a horned calf. The gene for scurs is carried separately to the horned gene.