Have you ever been puzzled by the vibrant colors of chicken eggs, especially those beautiful green ones? Understanding the genetics behind egg colors can be fascinating. Let’s dive into the science of chicken egg colors and explore what role blue and brown play in creating green eggs.
To understand egg color, we need to break down the genetics. Let’s start with the gene for blue eggs. There’s a specific gene pair that determines if a chicken will lay blue or white eggs. This isn’t linked to sex, meaning both male and female chickens carry and pass on these genes. For this gene, blue is dominant. This means if a chicken has just one copy of the blue gene, its eggs will have a blue base color.
Think of it like this: each chicken has two genes at this location, and they pass one to their offspring. If a chicken has two blue genes or two white genes, we know exactly what they’re contributing. But if a chicken has one blue gene and one white gene, it’s random which one they’ll pass on.
Let’s use symbols to make it clearer. We’ll use “B” for the blue egg gene and “b” for the white egg gene. If you cross a chicken with Bb genes (one blue, one white) with a chicken with bb genes (two white), some offspring will be Bb (laying blue eggs) and some will be bb (laying white eggs). If both parents are Bb, you’ll get a mix: some BB, some Bb, and some bb in their offspring, leading to both blue and white egg layers. This is the simple part of egg color genetics.
Now, where do green eggs come in? A green egg is essentially a blue egg with a layer of brown pigment on top. Imagine it like this:
- Blue base + no brown pigment = Blue egg
- Blue base + brown pigment = Green egg
- White base + no brown pigment = White egg
- White base + brown pigment = Brown egg
The brown color is where things get more complex. Many different genes contribute to brown egg color, which is why you see so many shades of brown and green. Scientists have identified at least 13 genes that influence brown color, and there are likely more yet to be discovered. Some of these genes are dominant, and some are recessive. The effect of some might even depend on the presence of other genes. Brown egg colors can range from a light “tinted” or pinkish hue to the deep chocolate brown of a Marans egg. Green eggs also exhibit a wide range of shades, depending on the amount of brown pigment layered on the blue base.
It’s often hard to pinpoint exactly which brown genes are present in your chickens laying green eggs. The more different brown genes involved, the more challenging it is to breed them out if you wanted to. And remember, recessive genes can hide for generations and then reappear.
If your goal is to breed chickens that lay bluer eggs, there are a couple of strategies. One approach is to selectively hatch eggs only from your hens that lay the bluest eggs and breed from those chickens. Over time, this can lead to bluer eggs, but it’s very difficult to completely eliminate brown pigment. It might even be impossible if certain brown genes are fixed in your flock, meaning both males and females have two copies of those genes.
Another strategy is to cross your bluest egg-laying hens with chickens that lay white eggs. White eggs have a white base color and, crucially, no brown pigment. Each generation of crossbreeding should help reduce the brown genes in your flock. However, a drawback is that about half of the offspring might lay white or brown eggs instead of blue or green.
Alternatively, instead of using white egg layers, you could introduce pure blue egg-laying chickens to your flock. These chickens also contribute no brown pigment. Of course, if your main goal is blue eggs, you might consider focusing solely on pure blue egg layers and phasing out your green and brown egg layers.
Understanding the genetics of egg color, and specifically What Does Green And Blue Make in chicken eggs, opens up a fascinating aspect of chicken breeding. It reveals that the beautiful green egg is a result of nature’s artistry, combining a blue base with a brown overlay, a testament to the complex and beautiful world of genetics.
