What’s Wrong With This Egg? Blood Spots, Double Yolks & Shells

Quick answer: most odd eggs are fine to eat. A blood spot is a tiny vessel that broke as the yolk was released, and USDA FSIS says it “does not indicate the egg is unsafe.” A double yolk is two yolks released together, usually by a young pullet, and Utah State Extension calls those eggs “completely safe to eat”. Yolk colour is the hen’s diet. The ones that go in the bin are an egg that smells bad, a pink or shimmering white, a cracked egg, a soft or missing shell and one caked in droppings. Pick what you see, and the checker gives the verdict, the words it rests on, and what to change in the run.

Inside the egg: spots, strings and two yolks

Nearly everything you find inside a fresh egg is a normal part of how it was made. A blood spot, in the words of the USDA’s grading manual: “Blood spots are caused by a rupture of one or more small blood vessels in the yolk follicle at the time of ovulation.” A brown or tan fleck is a meat spot — “either blood spots which have changed in color due to chemical action, or tissue sloughed off from the reproductive organs of the hen.” Utah State: “They are not harmful but are visually unappealing.” If you keep brown-egg layers you will see more of both, because the same manual notes that “the incidence of meat spots is significantly higher in brown eggs than in white eggs” and they are harder to spot when candling.

The white strings either side of the yolk aren’t a spot at all. They are the chalazae, “the twisted cord-like strands of egg white that anchor the yolk in the center of the white,” and they get weaker as an egg ages, so a strong, easy-to-see pair means a fresh egg. A cloudy white means the same: USDA FSIS says “A cloudy white (albumen) is a sign the egg is very fresh.”

Why a young hen lays double yolks

“Double-yolked eggs result when two yolks are released about the same time,” the grading manual says, and Utah State adds that it is “most frequently seen in young pullets whose reproductive systems are still developing”. They are safe to eat and a treat to find, but don’t put one under a broody or in the incubator: Utah State says “they are not suitable for hatching since they rarely develop into chicks.” The same young layers are the ones that lay the odd tiny egg with no yolk, and the odd one streaked with blood on the outside, while everything settles down. If you’re waiting on the first eggs, the first egg calculator says when to start looking.

Yolk colour is the feed

USDA FSIS: “The color of yolk varies in shades of yellow depending upon the hen’s diet.” Hens that eat greens, yellow corn or marigold petals lay darker yolks; Utah State notes that “When chickens eat heavy in wheat or barley, their yolks tend to be paler.” A reddish or olive raw yolk is also feed — the manual names “green grasses, silage, and cottonseed meal (gossypol not removed)” — but no source rates eating one either way, so the checker sends you to the usual check rather than calling it safe. A green ring round a boiled yolk is only the pan: “The green color is safe to consume.”

Thin, soft and missing shells

A shell is mostly calcium, and when there isn’t enough the shell shows it first. Utah State lists the usual reasons for thin or soft shells: “a deficiency of calcium or vitamin D, heat stress, or using hens that are too young or too old.” The University of Georgia adds that “Soft-shelled eggs are more likely to be observed in older hens.” For laying hens, the University of Kentucky’s answer is oyster shell on the side: “If hens produce eggs with thin shells or shells that are easily cracked, oyster shell supplementation might help.” Keep it away from birds that aren’t laying yet, though. Kentucky again: “If you feed high-calcium diets to growing chickens, kidney damage can result.” The feed calculator works out how much layer feed the flock actually eats.

The checker says to throw away a soft-shelled or shell-less egg rather than cook it. The shell is what keeps bacteria out, and on those eggs, as Georgia puts it, the inside is “protected only by the shell membranes.” That’s the “err toward don’t” rule this site uses for every food answer.

When it’s more than one odd egg

One odd egg means very little. Georgia: “Domestic egg production, whether on a large scale or in small and backyard flocks, will often result in some odd-looking eggs.” What matters is a change across the flock. The USDA’s list of the signs of highly pathogenic bird flu includes “Decreased egg production or soft-shelled or misshapen eggs”, and it asks keepers who see those signs in their birds to call: “report them immediately to USDA at 1-866-536-7593.” The Merck Veterinary Manual names other viral diseases that do the same. This checker won’t tell you which one — nobody can from an egg — but if several hens start laying soft or wrinkled eggs at once, and especially if any of them look unwell, that call and an avian vet come before any change of feed.

Dirty and blood-streaked shells, and the washing argument

A streak of blood on the shell is most common on a young hen’s first eggs, and Georgia says “these eggs can be cleaned to remove the stains.” How to clean one is where the official answers split. USDA FSIS: “It’s not necessary or recommended for consumers to wash eggs.” Penn State Extension, writing about eggs from your own flock, says you don’t have to — but if you do, “Agitate, but do not submerge, one egg at a time in water that contains a food-safe detergent and is at least 20°F higher than the internal temperature of the egg, and a minimum of 90°F.” The checker prints both. An egg caked in droppings is different: Georgia’s dirty eggs “would not be sold for human consumption,” and neither should yours be eaten. Collecting more often fixes most of it. For how long clean eggs keep, washed or not, use the egg float test.

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