The Dun gene acts on the base color, adding the characteristic dark dorsal stripe. In some cases it lightens the body tone and may also produce zebra-like leg markings. This coat is based on Black.
Typical Genetic Formula
E/_ a/a D/n
Possible Genotype Variations
E/e a/a D/n
E/e a/a D/D
E/E a/a D/n
E/E a/a D/D
The Genetic Basis
For a horse to be born Grullo, it must receive the following combination from its parents:
- Its ability to express or produce black pigment indicates it received the dominant E allele from at least one parent.
- To be visually black, it needed to inherit the absence of Agouti (a) from both sire and dam.
- The dark dorsal stripe and primitive markings came from at least one parent (D).
Understanding the Alleles
The horse Grullo has a specific combination of alleles. Below, we explain each genetic component that forms this coat:
- a/a (Non-Agouti): Allows black to spread over the entire body when combined with E. In e/e animals it is invisible but still passed on.
- D/ (Dun): Adds primitive markings (dorsal stripe) and may slightly lighten the base color.
