In today’s episode, I am talking with Noelle Leston about an interesting topic, horse colors and their genetics. Every horse owner and breeder should have a basic knowledge of genetics in order to understand how different traits, not only color, is passed from one horse to its offsprings. But it also makes a fascinating topic for conversations and it is not as complicated as you might think. Noelle and me chat about horse we have bred, different colors and how they are passed on and why a basic knowledge of genetics is useful.
Basic Horse Color Genetics
Genes & Chromosomes
The body of every living being is made up of cells. Each cell has the same set of genes, even though there are many different cells such as muscles cell, bone cell, skin cell, etc. Inside the cell the DNA is stored in the nucleus of the cell on different chromosomes. The horse has 64 chromosomes. On each of them we find the DNA which contains the genetic information. It consists of a double helix, similar to a twisted ladder.
A gene is a segment of the DNA which contains the information for a specific trait. Some are very short while others are very long segments. The DNA contains thousands of genes.
Each gene has a particular address which is called locus which is the specific location on the chromosome.
Each gene can have different variations called alleles which are responsible for the physical traits. Since chromosomes come in pairs, each horse has two alleles, one inherited from the mother and the other one from the father.
When both alleles are identical, the horse is homozygous for that gene.
When both alleles are different, the horse is heterozygous for a gene. Then the dominant gene will express itself while the recessive gene will not but can be passed on to an offspring.
We have to distinguish between the genotype and the phenotype of the horse. The genotype is the genetic makeup of the horse and consists of the different alleles which are present in the DNA but which might not get expressed because they are recessive. The phenotype is how the horse looks on the outside.
Dominant alleles are expressed even if the horse has only one copy of the allele. So we cannot see if the horse is heterozygous or homozygous for this allele. An example is the tobiano gene. Dominant genes are marked with a capital letter.
Recessive alleles are only expressed when the horse has two copies from them. Otherwise it is a masked alleles which cannot be seen but which might be passed on to off-springs. An example is the overo gene. Recessive genes are marked with a small letter.
In-complete dominant alleles have a dosage effect, they will express with more intensity when two copies are there. An example is the creme gene. In-complete dominant alleles are also marked with a capital letter.
The Punnett square is a great tool to predict possible offsprings based on the parents’ different genotypes. An easier way is to use a color calculator which will automatically give you all the different possibilities and probabilities.
Horse Color Chart
Why Should be know this?
- It helps us to know what color to expect in foals when we mate a mare with a particular stallion
- With this knowledge, we can increase the chances of a particular color
- We can avoid colors that are not desirable, pose health risks or are lethal to foals
Your Guest today:
Noelle Leston (USA)
Horse owner and breeder from the USA who has a deep interest and extensive knowledge of horse color genetics.
Don’t forget to check out the resources section in this article!
- How do genes work
- Basic colours and pigments
- Dominant, intermediate and recessive alleles
- Dun genes, pattern genes & newly discovered color genes
- Lethal genes
Thank you for tuning in and happy trails!
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- Color Calculator
- Horse Color Genetics Explained
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