Blue eyes in goats is considered a dominant trait, though it has been known to skip a generation or two and pop up later on when two brown eyed parents are bred together. Blue eyes are commonly found in Nigerian Dwarfs but also occur in Myotonic (Fainting) Goats & Angoras.
The biggest confusion with eye color is most breeders tend to assume they know which alleles their goats have. Just because a goat has blue eyes doesn’t mean it doesn’t also carry alleles for amber or brown, and just because a goat has amber or brown doesn’t mean it doesn’t carry an allele for blue.
a = amber, B = blue, n = brown (normal)
Example 1:
You breed your blue eyed goat with the alleles: BBnn to a blue eyed goat with the alleles: BBnn.
Breeding these 2 example goats together could produce the following:
- BBBB (blue eyed)
- BBBn (blue eyed)
- BBnn (blue eyed)
- BnBB (blue eyed)
- BnBn (blue eyed or possibly marble eyed due to 2 copies of the brown allele, though there are some who believe the marbling affect may have an allele of it’s own)
- Bnnn (brown eyed, carrying the allele for blue eyes)
- nnBB (blue eyed or possibly marble eyed due to 2 copies of the brown allele)
- nnBn (brown eyed, carrying the allele for blue eyes)
- nnnn (brown eyed)*Note the example parents above are possibly both marble eyed with those alleles.
Example 2:
You breed your blue eyed goat with the alleles: BBnn to a blue eyed goat with the alleles: BBBn.
Breeding these 2 example goats together could produce the following:
- BBBB (blue eyed)
- BBBB (blue eyed)
- BBBn (blue eyed)
- BnBB (blue eyed)
- BnBB (blue eyed)
- BnBn (blue eyed or possibly marble eyed due to 2 copies of the brown allele, though there are some who believe the marbling affect may have an allele of it’s own)
- nnBB (blue eyed or possibly marble eyed due to 2 copies of the brown allele)
- nnBB (blue eyed or possibly marble eyed due to 2 copies of the brown allele)
- nnBn (brown eyed, carrying the allele for blue eyes) *Note with the example parents above one is possibly marble eyed with those alleles.
Example 3:
You breed your brown eyed goat with the alleles: nnBn to a brown eyed goat with the alleles: nnBn.
Breeding these 2 example goats together could produce the following:
- nnnn (brown eyed)
- nnnB (brown eyed, carrying the allele for blue eyes)
- nnBn (brown eyed, carrying the allele for blue eyes)
- nBnn (brown eyed, carrying the allele for blue eyes)
- nBnB (blue eyed or possibly marble eyed due to 2 copies of the brown allele)
- nBBn (blue eyed or possibly marble eyed due to 2 copies of the brown allele)
- Bnnn (brown eyed, carrying the allele for blue eyes)
- BnnB (blue eyed or possibly marble eyed due to 2 copies of the brown allele)
- BnBn (blue eyed or possibly marble eyed due to 2 copies of the brown allele)
Example 4:
Let’s say for example you have an amber eyed goat with the alleles: aaBa . This basically means she has 3 copies of the allele for amber. Then your buck for example may be nnBn. This would mean he has 3 copies of the allele for brown. Breeding these 2 example goats together could produce the following:
- aann (amber or brown eyed, depending on which is more dominant… as far as I known there’s no study on this in goats)
- aanB (amber eyed, carrying the allele for blue eyes)
- aaBn (amber eyed, carrying the allele for blue eyes)
- aBnn (brown eyed, carrying the allele for blue eyes)
- aBnB (blue eyed)
- aBBn (blue eyed)
- Bann (brown eyed, carrying the allele for blue eyes)
- BanB (blue eyed)
- BaBn (blue eyed)
In saying the above, I’m not pretending to know which alleles for eye color your goats have, these are just some of many possible breedings.
Goat eye color is complex due to their being variances in eye color. It should also be noted that some goats have eyes in which only part of the iris is blue (this also occurs in dogs). Such animals are most likely heterozygous blue eyed and are considered genetically blue-eyed, even if only the tiniest portion of the iris is blue, and they can still have offspring with completely blue eyes. Some goats have one blue eye and one brown eye, though this is more rare. Two different colored eyes is controlled by totally different genetic markers so they could produce blue or brown eyed kids, or kids with different colored eyes like themselves.
When brown eyed kids appear from two blue eyed parents people are often confused, but this just means that the blue eyed parents are most likely both BBnn and both carry the gene for brown eyes. Others assume the brown eyes must be dominant because there are so many more brown eyed goats around. This is an inaccurate assumption because brown eyed goats bred to other brown eyed goats are going to produce brown eyed kids because both parents have two copies of the recessive brown eyed gene. The exception to this rule is when the brown eyed goats both carry 1 allele for blue eyes nnnB. (See Example 3 above). Breeding 2 goats that are both brown eyed but carry 1 allele for blue eyes can result in blue eyed or brown eyed kids. (Again, read through Example 3 above to see the possible results).
I am by no means a genetics expert, but I hope this will help. If you are interested in learning more about livestock genetics I recommend the book A Breeder’s Guide to Genetics.
