Sire Gray Smoky Black on dam Chestnut
In this article, we will explore the genetic possibilities of coat colors for the crossing between a stallion Gray Smoky Black and a mare 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 Gray Smoky Black. Genetically, it presents the base genotype E/_ a/a Cr/n G/n. The (G) gene acts on the base coat promoting progressive lightening throughout the horse's life until reaching very pale or completely white tones. This coat is based on Smoky Black.
On the other side, the mare Chestnut contributes with its genetics based on e/e. Base coat with a reddish body, mane and tail, with no black pigment.
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 Gray Smoky Black. it carries specific gene combinations. The possible genotypes for the sire include variants such as: E/e a/a Cr/n G/n, E/e a/a Cr/n G/G, E/E a/a Cr/n G/n, E/E a/a Cr/n G/G.
As for the dam, being Chestnut, may present in its DNA the alleles: e/e A/A, e/e A/a, e/e a/a.
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).
- G/ (Grey - Tordilho): Causes progressive greying. It is epistatic (covers other colors).
Calculated Probabilities
Being the sire Gray Smoky Black with genotype (E/e a/a Cr/n G/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 Grey allele (G).
Being the sire Gray Smoky Black with genotype (E/e a/a Cr/n G/G), 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 Grey allele (G).
Being the sire Gray Smoky Black with genotype (E/E a/a Cr/n G/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 Grey allele (G).
Being the sire Gray Smoky Black with genotype (E/E a/a Cr/n G/G), 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 Grey allele (G).
Being the dam 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 dam 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 dam 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).
Based on a standard scenario, the statistical chances for foals from this crossing are:
Gray BuckskinOpen Coat ➜ 9,8%
BuckskinOpen Coat ➜ 9,8%
Gray BayOpen Coat ➜ 8,8%
BayOpen Coat ➜ 8,8%
Gray PalominoOpen Coat ➜ 8,8%
PalominoOpen Coat ➜ 8,8%
Gray ChestnutOpen Coat ➜ 8,8%
ChestnutOpen Coat ➜ 8,8%
Gray Smoky BlackOpen Coat ➜ 6,5%
Smoky BlackOpen Coat ➜ 6,5%
Gray BlackOpen Coat ➜ 6,5%
BlackOpen Coat ➜ 6,5%
Gray Dark BrownOpen Coat ➜ 1,0%
Dark BrownOpen Coat ➜ 1,0%
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