Sire Chestnut on dam Smoky Black
In this article, we will explore the genetic possibilities of coat colors for the crossing between a stallion Chestnut and a mare 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 Chestnut. Genetically, it presents the base genotype e/e. Base coat with a reddish body, mane and tail, with no black pigment.
On the other side, the mare Smoky Black contributes with its genetics based on E/_ a/a Cr/n. Slightly faded black coat caused by a single copy of the cream gene over the black base.
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 Chestnut. it carries specific gene combinations. The possible genotypes for the sire include variants such as: e/e A/A, e/e A/a, e/e a/a.
As for the dam, being Smoky Black, may present in its DNA the alleles: E/e a/a Cr/n, E/E a/a Cr/n.
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/n (Heterozygous Cream): One copy of the dilution allele. Lightens red pigment to gold (e.g. Palomino, Buckskin).
Calculated Probabilities
Being the sire Chestnut with genotype (e/e A/A), 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.
Being the sire Chestnut with genotype (e/e A/a), 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%.
Being the sire Chestnut with genotype (e/e a/a), it transmits the (e) allele to 100% of offspring, allowing only red pigment expression (phaeomelanin) and transmits the (a) allele to 100% of offspring, allowing black to spread in homozygosis (if Extension is present).
Being the dam Smoky Black with genotype (E/e a/a Cr/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).
Being the dam Smoky Black with genotype (E/E a/a Cr/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).
Based on a standard scenario, the statistical chances for foals from this crossing are:
BuckskinOpen Coat ➜ 19,5%
BayOpen Coat ➜ 17,6%
PalominoOpen Coat ➜ 17,5%
ChestnutOpen Coat ➜ 17,5%
Smoky BlackOpen Coat ➜ 13,0%
BlackOpen Coat ➜ 13,0%
Dark BrownOpen Coat ➜ 2,0%
Want absolute precision?
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