This year, like every year, has been a busy one for America’s chickens. What the birds lack in smarts they make up for in work ethic, laying about 78 billion eggs annually (or 6.5 billion dozen), supplying a $7 billion industry. GM should be doing so well. Like any other workers, hens turn out economy, premium and luxury products — known as factory, cage-free and organic eggs — and consumers pay accordingly. A recent survey conducted in one random city — Athens, Ga. — found factory eggs going for $1.69 per dozen, cage-free for $2.99 to $3.59, and organic for $3.99 to a whopping $5.38.

But it’s worth it to pay more because you’re getting a healthier product, right? Wrong. Most of the time, according to a just-released study by the U.S. Department of Agriculture (USDA), the eggs are indistinguishable. When there is a difference, it’s often the factory eggs that are safer.

The study, led by food technologist Deana Jones, was not designed to explore the question of which egg-laying conditions are best for the hens themselves — simply because there is no question. Factory hens are confined in what are known as battery cages, which leave them crowded and all but immobilized, reduced to little more than egg-laying machines. Free-range and organic chickens have different degrees of freedom to move and are raised on varying levels of higher-quality feed. There’s no question what kind of life the birds prefer.

What Jones and her colleagues wanted to learn is whether a happy hen in fact produces a better product. To do that, they relied principally on something known as the Haugh unit — a highly specialized egg-quality metric developed by food technologist Raymond Haugh in 1937. The white of an egg is where all its protein is found; it’s made of both thin albumen — the watery fluid that runs farthest from the yolk when the egg is cracked into a cold pan — and thick albumen, the more viscous fluid that stays closer to the middle. The greater the amount of thick albumen, the more nutritious the egg. Read full story in Time.