Sire Grullo on dam Roan Smoky Black
In this article, we will explore the genetic possibilities of coat colors for the crossing between a stallion Grullo and a mare Roan Smoky Black. Equine genetics is a universe of combinations where dominant and recessive alleles determine the final coat of each individual.
On one side, we have the stallion Grullo. Genetically, it presents the base genotype E/_ a/a D/n. 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.
On the other side, the mare Roan Smoky Black contributes with its genetics based on E/_ a/a Cr/n Rn/n. The (Rn) gene acts on the base coat by distributing white hairs throughout the body, giving it a roan appearance. The head and legs retain the original base color tones. This coat is based on Smoky Black.
Quando combinamos esses códigos genéticos, criamos uma matriz de probabilidades. É importante lembrar que o resultado visual (fenótipo) muitas vezes esconde genes recessivos que podem pular uma geração.
The Genotypes Involved
For a horse to have the coat Grullo. it carries specific gene combinations. The possible genotypes for the sire include variants such as: E/e a/a D/n, E/e a/a D/D, E/E a/a D/n, E/E a/a D/D.
As for the dam, being Roan Smoky Black, may present in its DNA the alleles: E/e a/a Cr/n Rn/n, E/e a/a Cr/n Rn/Rn, E/E a/a Cr/n Rn/n, E/E a/a Cr/n Rn/Rn.
Understanding the Alleles
To understand the result of this crossing, note the gene sets at play:
- E/ (Extension - Dominant): The Extension gene controls eumelanin (black) production. At least one E allele allows the horse to have black hairs.
- a/a (Non-Agouti - Recessive): Allows black pigment to spread uniformly across the body. Essential for Solid Black (if E/).
- Cr/n (Heterozygous Cream): One copy of the dilution allele. Lightens red pigment to gold (e.g. Palomino, Buckskin).
- D/ (Dun - Primitive Gene): Dilutes body color and adds dorsal stripe and leg barring.
- Rn/ (Roan - Rosilho): Mixes white hairs throughout the body, keeping head and extremities in the original color.
Calculated Probabilities
Being the sire Grullo with genotype (E/e a/a D/n), it transmits the (E) allele (black factor) to 50% and the (e) allele (red factor) to the other 50% and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and has a 50% chance of transmitting the primitive Dun allele (D).
Being the sire Grullo with genotype (E/e a/a D/D), it transmits the (E) allele (black factor) to 50% and the (e) allele (red factor) to the other 50% and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and always transmits the primitive Dun allele (D).
Being the sire Grullo with genotype (E/E a/a D/n), it transmits the (E) allele to 100% of offspring, enabling black pigment production (eumelanin) and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and has a 50% chance of transmitting the primitive Dun allele (D).
Being the sire Grullo with genotype (E/E a/a D/D), it transmits the (E) allele to 100% of offspring, enabling black pigment production (eumelanin) and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and always transmits the primitive Dun allele (D).
Being the dam Roan Smoky Black with genotype (E/e a/a Cr/n Rn/n), it transmits the (E) allele (black factor) to 50% and the (e) allele (red factor) to the other 50% and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and has a 50% chance of transmitting the Cream dilution allele (Cr) and has a 50% chance of transmitting the Roan allele (Rn).
Being the dam Roan Smoky Black with genotype (E/e a/a Cr/n Rn/Rn), it transmits the (E) allele (black factor) to 50% and the (e) allele (red factor) to the other 50% and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and has a 50% chance of transmitting the Cream dilution allele (Cr) and always transmits the Roan allele (Rn).
Being the dam Roan Smoky Black with genotype (E/E a/a Cr/n Rn/n), it transmits the (E) allele to 100% of offspring, enabling black pigment production (eumelanin) and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and has a 50% chance of transmitting the Cream dilution allele (Cr) and has a 50% chance of transmitting the Roan allele (Rn).
Being the dam Roan Smoky Black with genotype (E/E a/a Cr/n Rn/Rn), it transmits the (E) allele to 100% of offspring, enabling black pigment production (eumelanin) and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present) and has a 50% chance of transmitting the Cream dilution allele (Cr) and always transmits the Roan allele (Rn).
Based on a standard scenario, the statistical chances for foals from this crossing are:
Roan Dun Smoky BlackOpen Coat ➜ 11,0%
Dun Smoky BlackOpen Coat ➜ 11,0%
Roan Smoky BlackOpen Coat ➜ 11,0%
Smoky BlackOpen Coat ➜ 11,0%
Roan Dun BlackOpen Coat ➜ 11,0%
GrulloOpen Coat ➜ 11,0%
Roan BlackOpen Coat ➜ 11,0%
BlackOpen Coat ➜ 11,0%
Roan Dun PalominoOpen Coat ➜ 1,5%
Dun PalominoOpen Coat ➜ 1,5%
Roan PalominoOpen Coat ➜ 1,5%
PalominoOpen Coat ➜ 1,5%
Roan Dun ChestnutOpen Coat ➜ 1,5%
Dun ChestnutOpen Coat ➜ 1,5%
Roan ChestnutOpen Coat ➜ 1,5%
ChestnutOpen Coat ➜ 1,5%
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