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Ep 54: The Colorful Life of Bird Eggs - Chickens and Turkeys

• Shekerah Primus & Fatu Badiane-Markey • Season 3 • Episode 22

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The egg color saga continues as Fatu and Shekerah look into how domesticated birds like chickens and turkeys got their egg colors. In the previous episode, we learned that the breed of chicken is responsible for egg color and this is all linked to the genetics of the rooster and hen. In the US for example, Leghorn chickens are the most common breed for egg-laying and they always produce white eggs, while Orpington’s lay brown eggs and Ameraucana lay blue eggs. Through many years of research, scientists have discovered exactly which genes in chickens are associated with egg color. For chickens that lay blue eggs like the Ameraucana and Dongxiang they both have the SLCO1B3 gene. And even more interesting, this gene has a specific mutation caused by an avian retrovirus that directly changes the way this gene is expressed to produce the blue egg color. So it is both the presence of the SLCO1B3 gene and the avian retrovirus mutation in Ameraucana and Dongxiang that is responsible for the trait of blue egg color. Even with the whole spectrum of the colors available to chicken eggs, consumer preference and culture ultimately determine what color eggs are sold around the world. Europeans have different color preferences compared to Americans and Japanese and this leads to the different egg colors across countries. To hear more about chicken egg color, and even turkey egg color listen to the episode. 

Tune into this episode to learn more about:

  • Bird egg color, genetics, and evolution
  • What specific genes are associated with bird egg color and how those genes are passed down with each generation
  • How an avian retrovirus is connected to blue gg color
  • Turkey eggs and how they get their colors

If you enjoyed this episode, check out one more:

  • Ep 44: The Colorful Life of Bird Eggs
  • Ep 38: The Secret behind CRISPR Gene Editing
  • Ep 39: The Art of Science - The Work

Sources:
Refine localizations of functional variants affecting eggshell color of Lueyang black-boned chicken in the SLCO1B3

An EAV-HP Insertion in 5′ Flanking Region of SLCO1B3 Causes Blue Eggshell in the Chicken

Reach out to Fatu:
www.linkedin.com/in/fatubm
Twitter: @thee_fatu_b
and LoveSciencePodcast@gmail.com

Reach out to Shekerah:
www.linkedin.com/in/shekerah-primus
and LoveSciencePodcast@gmail.com


Music from Pixabay: Future Artificial Intelligence Technology 130 by TimMoor
Music from https://freemusicarchive.org/music/Scott_Holmes: Hotshot by ScottHolmesMusic

This transcript was auto-generated using AI. If you would like a cleaner copy please reach out us at We Love Science podcast. 

Intro  0:01  
What can you do with your love of science? We'll tell you.

Fatu Badiane Markey  0:28  
Hello everyone, and welcome back to the show. We love science. My name is Fatu

Shekerah Primus  0:33  
And I'm Shekerah, and today we are going back to Birdland to learn more about how bird eggs get their color, specifically for domesticated birds like turkeys and chickens. Ooh, okay,

Fatu Badiane Markey  0:49  
And it's gonna be eggs exciting. Y'all. You know? You know, I had to throw a pun in there because they're just worried enough of them last time. Yeah,

Shekerah Primus  1:01  
Sure,

Fatu Badiane Markey  1:03  
Shekerah, I'm ruining all my puns. So Shekerah, how are you before we get started,

Shekerah Primus  1:09  
I am doing well today, enjoying my trusty apple a day. How about yourself? How are you doing?

Fatu Badiane Markey  1:15  
Very nice. I'm doing good. I'm doing good. It's been a pretty productive Sunday for me. Got all the chores out of the way. The laundry is done, and it's not even like 7pm which is, for me, like a great deal,

Shekerah Primus  1:32  
You do laundry late,

Fatu Badiane Markey  1:33  
Girl, because I'm always, I'm always putting it up. So before we get into a color Shakira, let's start with a little food science talk. I feel like we haven't done enough on the sweets lately. So what is your favorite candy or chocolate bar?

Shekerah Primus  1:48  
So that is kind of an impossible question for me to answer.

It's probably easier for

me to answer which chocolate I do not like, okay,

Fatu Badiane Markey  2:01  
You can also do top three.

Shekerah Primus  2:05  
I like them all, okay, so I'm just gonna pick a couple. So good all in the nuts. Those are always a good bet. I feel to hit the spot, you know, and they're pretty easy to find. I prefer the ones with peanuts in it. I guess probably similarly, I also like peanut Chews. It's these little like bars of dark chocolate mixed with peanut mixed in and it's kind of like a chewy type of not a crunchy, but more of a chewy type of snack. I really enjoy those too. They hit the spot as well. So those are, those are two that I tend to go to quite frequently.

Fatu Badiane Markey  2:50  
Okay, nice. That's a good list. So I also am a big fan of the peanut butter chocolate variety. And my go to is Reese's. When my mom came, literally asked her, I and I have, like, now, like a huge bag of it. It's slowly, slowly windling down. So I might have to make another request to get somewhere over here. But I think that's, that's my favorite for right now.

Shekerah Primus  3:19  
Oh, you know what, now that I'm actually thinking about it. So one type of like chocolate that I like to that's kind of like the fancier chocolate in my head anyway, like to get a lot, is that like Ferrero Rocher chocolate, you know, the one that the little like golden wrapper.

Fatu Badiane Markey  3:42  
So, really good,

Shekerah Primus  3:44  
Yeah. That was amazing. And it has a peanut. It has a hazelnut in the middle, right, yeah. And then they have this coconut variety, oh, I don't know this one too that I really coconut, yeah,

Fatu Badiane Markey  3:57  
really, yeah.

Shekerah Primus  3:59  
It has like, coconut shavings on the outside, like Coconut, coconut is really good. I love that one. Okay, I have to find that. So I guess that would be my that would be my top, like, fancy candy, like that. And then everyday candy m&ms and peanut juice, yeah, those

Fatu Badiane Markey  4:15  
Are good. Those are good, especially the peanut m&ms or the peanut butter m&ms or the crispy m&ms. Those three are really good. All right, awesome. So let's get into it.

Shekerah Primus  4:28  
Yes, ma'am. So okay, we did a part one to this already, which was amazing. I learned so much. So we'll put a link to that in the show notes, so you guys can find it. So part one though, you tended to focus more on sort of more wild birds, I guess. And wild birds, yeah, birds in general, they're most, most of them are wild, right? And you know, sort of the evolutionary perspective of how they got their egg color. And so we learned that egg color co evolved with openness building in birds. So it went from covered or closed nests, which is, I think, what we would all think to do to protect our little babies, right? And those eggs would have white or brown color. And then it evolved to open nests with colors of all kinds, the blues and the greens and the gold and all the really cool things. So leaving eggs in an openness left them vulnerable to predators, of course, and so adding color may have proved as an evolutionary advantage to camouflage the eggs from predators, to keep the eggs at a consistent temperature, or to distinguish imposter eggs from your own eggs, right? So some birds, like the parasitic cockatoo we learned, like to have their eggs and then sneak them into someone else's nest and be like, Hey, take care of my eggs. To distinguish parents eggs from some parasitic cockatoo with some other bird that was trying to, like, sneak their eggs into their nest. So scientists don't exactly know how egg color evolved in birds, but think it's linked to survival in the wild, such as protection against the environment, camouflage, or even protection from parasites and for bacterial resistance. And with chickens, the color of a chicken egg is mainly determined by the chickens genetics. So chickens are highly, highly domesticated, right? It's much easier to find domesticated chickens than wild chickens, right? So that means that the breed of hen will usually indicate what color of egg will be produced. So go back and listen to episode one of bird color to learn more about all of these things. So what are you teaching us today? Fatu, yeah, and

Fatu Badiane Markey  7:06  
That was a great recapture. Kara, so you took some good notes. That's all I got to say you did. So today I'm going to continue talking about the last point. So domesticated birds, like chickens and turkeys, and what does it exactly mean when we say that their genetics determines their egg color? So you'll remember that when we discuss chickens, I mentioned the different breeds and the egg colors associated with them. So you have Leghorn chickens, which are really common in the US, and they lay white eggs. You have Orpingtons, which lay brown eggs, and then Americana, which lay blue eggs, and then you have even like olive Egger breeds, which are kind of like specialty breeds, and they lay olive green eggs. Yeah, right. So basically, what this means is that there are different genes from both roosters and hens that account for a color, right? And it's similar to how we think about maybe how our hair color and eye color is inherited from our parents, that it's like we're getting something from mom and something from dad, and that is leading to the trait that we see. So a few of the genes that have been associated with chicken egg color are al as one, SL, one, b3, HMO, x1, and A, B, C, g2,

Shekerah Primus  8:34  
They missed a couple letters there. A, B, C, D, E, F, G. They

Fatu Badiane Markey  8:40  
Did right? I was gonna say these gene names aren't like that exciting, but they have exciting stories behind them, so I'm gonna focus on this SL, CO, one, b3, and this gene is associated with blue, a color, and it's been studied in Dong Xiang chickens from China, and I'm sorry if I didn't say that properly, and also in Americana chickens, which are commonly found in the Americas, and both of those breeds of chickens lay blue eggs. So what's going on here? So some studies you know, have directly linked SL, CO, one, b3, to blue egg color, which means that the hens that lay these eggs are expressing this gene, and it's being expressed in their shell gland or in the chicken uterus, the hen uterus, which is where the pigments are deposited onto the eggs. This

Shekerah Primus  9:38  
Is so cool. I love that you picked chickens that lay blue eggs, because I do not believe I've ever eaten a blue egg. What parts of America are known for these fancy Americana chickens that lay their blue eggs? I really need to go there and eat some blue eggs. Yeah.

Fatu Badiane Markey  9:59  
No, that's a good question. I feel like you can come across blue eggs, but you definitely gotta look. It's not like, it's not like. I don't know if Trader Joe's is carrying blue eggs, but it's been like, very sporadic. You know what? I mean, yeah, yeah. Wonder

Shekerah Primus  10:20  
If they're popular. People would be like, ooh, blue eggs.

This is so weird. I'm not buying this

Fatu Badiane Markey  10:28  
From what I

remember. I think these chickens are originate from Latin America, and then they were brought up to the US, if I remember correctly. So, yeah, so maybe we just got to go down south, and then, you know, get those blue eggs.

Shekerah Primus  10:46  
All right. Okay, so chickens that lay blue eggs, you said they express this gene, SLC, A, one, d3, so does that mean that the chickens that lay brown eggs, for example, do not have this gene,

Fatu Badiane Markey  10:59  
Yeah. So that's correct. So in these studies, this SL, CO, one, b3, was not found in hens that lay non blue eggs, so for example, hens that lay brown eggs. And what is actually even more interesting is that there is a specific mutation associated with this blue egg color, right? So this the plot thickens. And so this is caused by the insertion of a retrovirus into this specific gene. And the retrovirus is called E, A, V, H, P, or endogenous avian retrovirus. And the word retrovirus might sound kind of familiar, because as humans, right? There's also a retrovirus that affects us, HIV, right? And what makes retroviruses really interesting is that they have a way of inserting or sticking their own genetic material into the DNA of the host. So in the case of blue egg laying chickens, at some point where

a part of these

Shekerah Primus  12:29  
Chickens today. Wow, that's a really cool story about this SL co gene and how it contributes to egg color. But you said that the chickens without this gene have brown eggs, but the chicken with this gene have blue eggs because this retrovirus added its DNA to the gene. Does that mean that if you remove the retrovirus, the retrovirus DNA part from the gene, that the eggs will no longer be blue? How does how does that work?

Fatu Badiane Markey  12:55  
No, that's a great question, and so I don't have the full story. But based on, you know, the different research articles I read to me, it sounds like the eggs are blue specifically because this mutation exists. So for example, in the Americana chickens and the other chicken variety that comes from China, they both have this insertion of the retro virus gene, but it's not and it's close to this SL, CO, one, b3, Gene. But where this retrovirus has inserted in each of those chicken strains is slightly different, so it has something to also do with insertion of the retrovirus itself, not just necessarily having the gene. And somehow, what I understanding from researchers who are looking at this, because the retrovirus has inserted itself in the DNA, it's messing up the function of that gene, and somehow that's leading to this phenotype of blue eggs,

Shekerah Primus  14:02  
Some mutations result in pretty colors. Very cool. Yeah, I'd love to know more about what that retrovirus is. Okay, so what does all of this have to do with egg color being inherited by the mother and father, chicken or hen, Rooster. You mentioned it's similar to hair color eye color in humans. Yeah, yeah. So how does that? How does that work? Yeah,

Fatu Badiane Markey  14:33  
No, that's a really great question. So to answer this, this blue egg color also follows what we call autosomal dominant inheritance patterns, which is the same as how we inherit hair color and eye color. It can get a bit more complicated as you go down from the middle lineage. So we'll keep it we'll keep it simple, we'll keep it simple, but basically what that means is that both parents are contributing, and then you're going to see a specific phenotype, right, a specific physical trait that is going to reflect the dominant gene. So with the chickens, if, for example, let's say I made a pure bread hen and Brewster that are from a lineage of blue egg laying chickens, I will get blue eggs and only blue eggs, because those are the only right? Because only that gene for blue eggs is being expressed by both the parents, right?

Shekerah Primus  15:31  
So you'll get very so you'll get very, very blue eggs. So they will be super blue.

Fatu Badiane Markey  15:37  
Yes, that's a good way to thinking about it, but we super blue. So as blue as is chickenly possible, the way that I'll think about it, yeah, but now, if I take, let's say my rooster is just from that, it's like a purebred lineage, and then I made it with a brown laying hen, I'll still get some blue in there, but it's going to be slightly less blue, right? Because the father is still contributing the blue colored gene. The mother, the hen, doesn't have it. So then what I'm seeing is kind of like a mix of the two, but now last scenario, right? If I take a rooster and a hen that are from a brown egg laying lineage. There's no gene in there for blue eggs, and so there's no way for me to get blue eggs there, because those genes just aren't expressed from that pair.

Shekerah Primus  16:34  
Okay, so that makes sense. If the gene is not there, then it's like, of course, the you know the trait is not present at all in the DNA, so you won't get blew it. So that makes sense Exactly,

Fatu Badiane Markey  16:46  
Exactly. And most of the articles are referenced for this. They're going to be in the show notes. So audience here, welcome to read them for yourselves as well. And they were published within the last 10 years, which makes me think that there's still a lot we don't know about egg color, even in domestic birds, like chickens, and even with all this egg colored chickens is still primarily influenced by consumer taste and preference. So overall, we want to buy eggs that look clean, glossy and good, maybe even we would describe them as like, tasty, somehow looking tastier, looking like, you know, looking like a nice little like snack or breakfast, right? But yummy. I mean, this is very different for every culture, yeah, so. And even when we're looking at different countries, there can also be different preferences. So in the US and Japan, for example, we prefer white eggs. In Europe, you usually see brown eggs, and in China, you can easily find pink or brown eggs, which is pretty cool.

Shekerah Primus  17:48  
Wow, fancy now,

Fatu Badiane Markey  17:52  
Yeah. Now, despite your preference for a color, one thing that holds true across the board is that a color has no impact on the nutritional value or content of an egg. What's inside the egg is exactly the same no matter the color. Sometimes you'll hear people say that you know, like brown eggs are healthier, or you know, they have more nutrients, or this and that, but it honestly just isn't true. The taste or nutrients found within an egg are more likely to be influenced by hen's diet and how hen was raised, but not a color at all.

Shekerah Primus  18:27  
Gotcha. I think that's a really important point you just made. Yeah, because you do have that, I feel like that shred for everything, right? Brown sugar is more healthy. Brown rice is more healthy. That isn't true for bird eggs, right? For bird eggs, the color of the egg has the egg shell, right? That's the outside of the egg that has absolutely nothing to do with the nutrients. That's a that's a good point. I like that exactly.

So is this also true for other domestic birds, like turkeys?

Fatu Badiane Markey  18:58  
So turkeys are really interesting. They also lay eggs, but not at the same rate of chickens, the US and then a lot of other places. You just don't see Turkey eggs for sale in stores because it's not, you know, economical to do that. We don't breed turkeys for their eggs. There is a lot less information available on turkey egg color and how that came to be, because we just don't care. From my research, Turkey eggs are speckled, and they tend to be bigger and harder, like the shell itself is actually harder with chicken eggs, and they their eggs are edible, so you can eat them, no problem. But other than that, there's nothing we just or just, like, not into the turkeys, at least Turkey, I should say, Yeah,

Shekerah Primus  19:50  
That's interesting. I wonder if they taste different than chicken eggs and like, what's Did you say the nutrition content was the same? Like, what's the nutrition content? Like, why aren't they popular Turkey eggs? I don't know. Interesting. Yeah,

Fatu Badiane Markey  20:08  
So nutrition content is about the same, you know, because they are bigger, you can you can see that they have, like, a little bit more calories, a little bit more protein, more cholesterol, you know, it's also some of the bad things that we don't want. But it just takes Turkey so long to lay eggs, you know, like that whole, I guess, process of making an egg takes more time, so chickens just do it much more efficiently, and in a way where you can actually make money selling chicken eggs, you know, I think I was reading like, say, like, one or two eggs a day. And a turkey is, like, one egg every few days, right? It's just like, you know, if you need a dozen eggs, you're gonna be waiting a month for a turkey. Where's a chicken? You could get that in like, a week, you know? Yeah,

Shekerah Primus  21:00  
It's the economics of the situation. I get it. So now we gotta do is, you know, use CRISPR and do some genetic editing to get easily eggs faster.

Fatu Badiane Markey  21:13  
Maybe there's a market for it somewhere, I don't know, because people also eat duck eggs, right? Like so I don't know, but one really interesting thing that you mentioned right now with CRISPR that I also thought of, and maybe this will be kind of like the next round of research, especially looking at these birds and their blue egg color and the gene that we know is associated with it. What would happen if you took a chicken that's supposed to lay blue eggs, and you crispered out that one gene that SL, CO, one, b3, right? And you also crispered out the retrovirus, would you lose the egg color? And then on the flip side, can you put that into a chicken that's supposed to lay white eggs and get blue eggs, right? So I'm just like, ah, these experiments haven't been done yet. It's not complete, but that would be really, really cool to see.

Shekerah Primus  22:09  
Yeah, we need more color researchers. It sounds like we

Fatu Badiane Markey  22:13  
Do, we do and all of this, yeah, talk about a color has also made me think about eye color in humans, right? I gave that analogy earlier on, and I was watching this really short clip about eye color in humans on YouTube, and it seems really fascinating. So I think my next sign shorty is going to be on eye color. So watch

Shekerah Primus  22:37  
Out for that, guys, nice. We're keeping the color theme. Excellent. Well, thank you so much Patu for teaching us all about color and our special domesticated birds, chickens and turkeys.

Fatu Badiane Markey  22:53  
No problem. I hope you learned a lot.

Shekerah Primus  22:57  
I learned a lot, and I hope you guys, listeners learned a lot as well. So we'd like to thank you guys for listening to another episode of our podcast. If you'd like to reach out to us, please send us an email at lovesciencepodcast@gmail.com Until next time bye, guys!

Transcribed by https://otter.ai