Sire Smoky Cream on dam Roan Chestnut
In this article, we will explore the genetic possibilities of coat colors for the crossing between a stallion Smoky Cream and a mare Roan Chestnut. 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 Smoky Cream. Genetically, it presents the base genotype E/_ a/a Cr/Cr. Very pale coat with yellowish highlights, resulting from double dilution of the cream gene over the black base.
On the other side, the mare Roan Chestnut contributes with its genetics based on e/e 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 Chestnut.
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 Smoky Cream. it carries specific gene combinations. The possible genotypes for the sire include variants such as: E/e a/a Cr/Cr, E/E a/a Cr/Cr.
As for the dam, being Roan Chestnut, may present in its DNA the alleles: e/e A/A Rn/n, e/e A/A Rn/Rn, e/e A/a Rn/n, e/e A/a Rn/Rn, e/e a/a Rn/n, e/e a/a Rn/Rn.
Understanding the Alleles
To understand the result of this crossing, note the gene sets at play:
- e/e (Red Factor - Homozygous Recessive): Determines the inability to produce black pigment, resulting in an exclusively red base coat (Chestnut).
- E/ (Extension - Dominant): The Extension gene controls eumelanin (black) production. At least one E allele allows the horse to have black hairs.
- A/ (Agouti - Dominant): The Agouti gene controls black distribution. The A allele restricts black pigment to the points (mane, tail, legs).
- a/a (Non-Agouti - Recessive): Allows black pigment to spread uniformly across the body. Essential for Solid Black (if E/).
- Cr/Cr (Double Cream): Maximum dilution. Pink skin, blue eyes (e.g. Cremello, Perlino).
- Rn/ (Roan - Rosilho): Mixes white hairs throughout the body, keeping head and extremities in the original color.
Calculated Probabilities
Being the sire Smoky Cream with genotype (E/e a/a Cr/Cr), 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 Cream dilution allele (Cr).
Being the sire Smoky Cream with genotype (E/E a/a Cr/Cr), 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 Cream dilution allele (Cr).
Being the dam Roan Chestnut with genotype (e/e A/A Rn/n), it transmits the (e) allele to 100% of offspring, allowing only red pigment expression (phaeomelanin) and transmits the (A) allele to 100% of offspring, restricting black pigment to the extremities and has a 50% chance of transmitting the Roan allele (Rn).
Being the dam Roan Chestnut with genotype (e/e A/A Rn/Rn), it transmits the (e) allele to 100% of offspring, allowing only red pigment expression (phaeomelanin) and transmits the (A) allele to 100% of offspring, restricting black pigment to the extremities and always transmits the Roan allele (Rn).
Being the dam Roan Chestnut with genotype (e/e A/a Rn/n), it transmits the (e) allele to 100% of offspring, allowing only red pigment expression (phaeomelanin) and transmits the (A) allele (restriction) to 50% and the (a) allele (no restriction) to the other 50% and has a 50% chance of transmitting the Roan allele (Rn).
Being the dam Roan Chestnut with genotype (e/e A/a Rn/Rn), it transmits the (e) allele to 100% of offspring, allowing only red pigment expression (phaeomelanin) and transmits the (A) allele (restriction) to 50% and the (a) allele (no restriction) to the other 50% and always transmits the Roan allele (Rn).
Based on a standard scenario, the statistical chances for foals from this crossing are:
Roan BuckskinOpen Coat ➜ 19,5%
BuckskinOpen Coat ➜ 19,5%
Roan PalominoOpen Coat ➜ 17,5%
PalominoOpen Coat ➜ 17,5%
Roan Smoky BlackOpen Coat ➜ 13,0%
Smoky BlackOpen Coat ➜ 13,0%
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