Egg Basics

I went out for dinner with an old friend the other night, a friend  who I’m a little ashamed to say I haven’t seen much of recently (I’m admitting that so that this becomes my public reminder to do better). We had a lot to talk about – my new job, her grad school research, our families, our friends, how delicious dinner was and my blog came up.  She, like many other people in my life, had read the first post and was very supportive of me. She asked me what I was going to write next. I told her I wasn’t sure and I was a little stuck.

Don’t get me wrong, I love writing and I have a couple half-finished posts sitting in my drafts folder.  But I wasn’t really sure which one I should start with.  Do I dive in to current ag topics like Dairy Farmers of Canada changing their logo or how Donald Trump hasn’t picked a Department of Agriculture Secretary yet? Do I go for the perpetual hot-button topics like GMO food, hormones and antibiotics in meat, or animal welfare? Or do I find my favourite science myths and start ranting about them?

My friend talked about her research on feeding behaviour in dairy cows and how she had a new volunteer in the lab who didn’t come from a farming background, much like the both of us.  This volunteer was apparently amazed at how much cows poop (if you’re wondering, they poop a lot). We started swapping stories of the things we had been amazed to learn about agriculture (chickens rely on only one ovary to produce their eggs, non-castrated male pigs produce off-flavoured meat) and it clicked that maybe starting with the very basics, at least until I had enough of an archive built up to reference back to, would be a good place to begin.

With that in mind, I would like to offer you a quick crash course in different eggs at the grocery store, since eggs and chickens are what I know best.

White vs Brown Eggs: You may have noticed a price difference between white and brown eggs, usually about 10¢ more per half dozen for brown eggs.  This is because chickens that lay brown eggs eat more food than chickens that lay white eggs, so there is a higher feed cost associated with producing brown eggs. Some people believe that there is a nutritional difference between white and brown eggs but when you break down the components, they have the exact same nutritional value.  The brown colour of egg shells is actually a pigment that is deposited on the shell in the 90 minutes before a bird lays it.  If you look at the header photo on this post, you’ll see that there’s a variety of different shades of brown that eggs can come in.  These are sorted out at an egg grading station, so that the whole eggs you see in a carton in a store look nice and uniform.  The other eggs are still completely edible, just not as quickly purchased at a grocery store, so they go into the breaker market.

Blue and Green Eggs: These actually exist. You won’t find them in big North American grocery stores but people with hobby farms might have some coloured egg layers around for fun. Blue eggs come from specific breeds of chicken, like the Ameruacana chickens, and the blue pigment goes through the shell, so the eggs are blue on the inside (as opposed to brown eggs, which are white on the inside).  Green eggs are produced by cross breeding a blue egg laying breed with a brown egg laying breed.

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Blue and brown eggs. Source: Autumn Mott, StockSnap

Omega3 Eggs: These are a relatively new addition to the egg shelf.  The chickens that produce these eggs have flax seed or fish oil included in their diets and that allows them to lay eggs with higher amounts of Omega3 in them.  The increase in this good fat may not be the best source of Omega3 though, so it is still better to rely on eating oily fish like salmon or trout. The Globe and Mail did a good article on Omega3 eggs a couple years back.

Enriched Cages, Free Run, and Free Range: All of these labels explain how the chickens who laid the eggs were housed. The Egg Farmers of Alberta have a nice little summary of all the different housing styles, including a fact sheet with a comparison of welfare in different housing styles. Conventional cages are what has been used in Canada for decades and are essentially cages that just have food and water in them. They are no longer allowed to be built in Canada and will be completely out of use by 2036.  That seems like a long time from now, but it is hard to overhaul an entire supply chain. Enriched or furnished cages allow for more space for the birds, perches, scratch pads and nest boxes.  Free run means that the birds are loose in the barns, with nest boxes and perches available.  In some instances, these barns can have different levels for the chickens to hop and fly up to.  Finally, free range is similar to free run, but the birds spend time outside as well.  This one can be a little challenging for a few reasons, most notably the 5-month-long-hell all Canadians must endure, called winter. Like myself, chickens are happiest at a comfortable 20·C temperature and if the weather is too cold or too hot, the birds can get cold or heat stressed, respectively, so there’s only certain temperatures when they can comfortably go outside. There is also some concern with wild birds shedding disease (like avian influenza) or a predator attack with free range birds.  Ultimately, it is up to a farmer to decide which housing system works best for them.

Fertile Eggs: This last one drives me nuts. In Canada, no eggs in a supermarket are fertile. A hen will lay an egg regardless of whether she has mated with a rooster and in Canadian egg barns, there are only female birds thus making fertilization impossible. Some people claim that they bought eggs at a grocery store and “saw a chick starting to form”. Chances are, they saw some white, squiggly, tissue-like material attached to the yolk.  These are called the chalaza and are proteins designed to keep the yolk suspended in the right spot in the shell.  They are seen mostly in fresh eggs, and the older an egg gets, the less visible the chalaza will be.

Hopefully this summary gives you a better sense of what all the labels on the egg shelf in the grocery store mean!

A photo by JOHN TOWNER.
I’m including this picture solely because I think it’s really funny. It’s like the hen is modelling for the camera. Source: John Towner, StockSnap