Blood in Chicken Egg: What Does It Mean?

When you raise your own flock of backyard chickens long enough, you will likely encounter all kinds of odd eggs, including blood in chicken eggs. From tiny fairy (or wind) eggs to oversized eggs, wrinkly eggs, spotted or streaked eggs, deformed eggs, thick-shelled eggs, thin-shelled eggs … you name it and you’ll likely collect a wide assortment from your chicken nesting boxes.

A chicken lays an egg about once every 26 hours, and the process her body goes through to lay an egg is so complex and needs to be so carefully orchestrated, it’s no wonder that sometimes eggs come out looking a bit strange. Odd things can happen inside the egg too. Some fairly common occurrences include eggs containing no yolk, double yolk eggs, white strands, blood spots, bullseyes … the list goes on.

When you purchase commercially farmed chicken eggs, likely you won’t encounter any eggs that are out of the ordinary, like you will from your own farm. It’s not because there’s something wrong with your chickens, not in the least, instead, it’s a function of how commercially sold eggs are selected.

Not only are the eggs visually inspected and sorted by color and size so the entire carton consists of virtually identical eggs, commercially sold eggs are also candled—meaning a bright light is shined into the egg to check for impurities or irregularities inside the egg. Those containing anything out of the ordinary are set aside and not put in a carton to be shipped to the grocery store shelves and offered for sale. Instead, they might be used in animal feeds. But when you start raising backyard chickens (or buy eggs from a local farm or farmers market), it’s likely you might crack an egg open to find a bit of a surprise. One of these surprises might be blood in the egg.

Blood in chicken eggs is often, mistakenly, believed to signify that an egg is fertile. This couldn’t be further from the truth. In fact, the true sign that an egg is fertile is a white “bullseye” on the yolk. This bullseye is the tiny bit of rooster DNA, which doesn’t change the taste or nutrition of that egg at all. It just means that egg will hatch if incubated at the correct temperature for the requisite 21 days.

So what does blood in chicken eggs signify? You might be surprised.

Blood in Chicken Egg

A red spot of blood in a chicken egg is actually a ruptured blood vessel. Each egg contains blood vessels that will eventually become lifelines to the developing embryo if that egg is fertilized and subsequently incubated. But even non-fertile eggs contain minuscule blood vessels which anchor the yolk inside the egg. If one of these blood vessels is broken during the laying process, which can happen if the hen is startled while she’s forming the egg or if she’s handled roughly, then it will show up inside the egg as a red blood spot. Sometimes there might be multiple blood spots, or the “white” of the egg  (the albumen) can be tinged with blood as well.

It’s estimated that between two to four percent of eggs laid contain a blood spot. The actual cause of blood in chicken eggs can vary. Blood in chicken eggs can be genetic, might be caused by lighting the coop through the winter, exposing the chicken to excess light and not give her enough time in darkness to produce adequate melatonin or by excess levels of Vitamin A and K in the hen’s diet. More serious causes can include fungus or toxins in the feed or Avian encephalomyelitis, but these are rare.

Generally though, blood in chicken eggs is not anything to be concerned about. You can eat an egg you find with blood in it. You might opt to remove the blood spot with the tine of a fork or the tip of a knife if you prefer, prior to cooking the egg for aesthetic reasons, but it’s perfectly edible. Even an egg with a bloody egg white is edible, although I admit a bit distasteful!

Egg Facts

Egg facts are fascinating and also good to know if you are raising chickens for eggs. From blood in chicken eggs, to bullseyes on the yolk, to the ropy chalazae which are strands of protein that anchor the yolk in place, to how to tell if eggs are bad, it’s up to you to know if the eggs you collect from your chickens are safe to eat – and safe to give or sell to friends, neighbors or at a farmers market.

You’ll be relieved to know that the chalazae, blood spots, and the bullseye don’t change the taste or edibility of an egg. There is no need to worry about candling the eggs you sell to try and determine if they contain anything odd.

While we’re on the topic, different colored chicken eggs all taste the same and look the same inside. The taste of an egg is determined by the freshness of the egg and the overall diet of the chicken, not by the breed of chicken or by the color of the egg.