So, Can Chickens Eat Onion?

Chickens are omnivorous and some might say adventurous eaters. There is hardly anything they will not eat, though there are a few items that seem to be controversial among owners.

newly introduced chickens to the flock
Newly introduced chickens to the flock. The black ones are the new additions.

One such item potentially on the menu is onions. Some owners are adamant that onions are completely safe and nutritious for chickens, while others say just the opposite.

This debate rages online. But what is the real story? Can chickens eat onions?

No, chickens should not eat onions. Onions and similar vegetables have the potential of causing serious health effects by disrupting red blood cells and causing anemia. Ingesting onions is also known to taint the flavor of both eggs and meat. Though tiny amounts of onions are likely not dangerous, it is better to be safe than sorry.

Although it provokes strong reactions and opinions on both sides, we don’t need to give in to arguing to get the scoop on feeding onions to chickens.

Keep reading and you’ll learn everything you need to know.

Onions are Toxic for Chickens

Make no mistake: onions can be harmful to chickens. Onions and related veggies in the allium category contain sulfoxides and disulfides, which can damage red blood cells and cause anemia, aside from other harmful side-effects.

These compounds, found in onions, garlic, leeks and other plants, are typically only harmful in high concentrations. But even a small amount of onion can potentially disrupt a chicken’s delicate red blood cells.

For example, let’s say your chicken ingests a small amount of onion every day. Though the effects might not be immediately noticeable, over time, the sulfoxides and disulfides will begin to take their toll and cause anemia.

Worse, it is impossible for any simple, visual examination to determine how much of the toxic compounds are present in any given onion.

This means that a small serving of one type might not cause any real harm, while even a small bit of another could be enough to cause lasting injury or death.

Ingesting Onions May Result in Tainted Eggs or Meat

Perhaps the most harmless but most noticeable side effect of ingesting onions is the potential for your chicken’s eggs and meat to take on an oniony or sulfur-like flavor.

This is because the compounds that make onions so harmful to chickens are also responsible for their signature taste and smell.

When these compounds are present in a chicken’s system, they will likely end up in the bird’s eggs and meat as well.

Of course, this is only a problem if you plan on eating your chicken’s eggs or meat. If you don’t, then there is no real reason to worry about this particular issue, though there are plenty more.

Effects of Onion Toxicity

Even though onions are not something that is instantly deadly or poisonous to chickens like henbane, yew or various poison mushrooms, it can still prove to be quite harmful after they eat enough.

The usual symptoms owners should watch out for include weakness, depression, diarrhea, breathing troubles and a loss of appetite.

More serious cases might also result in anemia, which is often accompanied by pale combs and wattles.

It is anemia that is the major problem associated with eating onions, and one that can be difficult to treat.

Thiosulfate can cause what is known as Heinz body anemia in chicken; it causes the red blood cells to degrade until they are unable to transport oxygen throughout the body.

Thiosulfate has also been shown in research to induce methemoglobinemia, which is when the iron in red blood cells is no longer able to bind with oxygen.

This type of anemia is serious and can often be fatal if not treated quickly and correctly. If you think your chicken might be suffering from anemia, take it to a vet as soon as possible for treatment.

Eating Even a Little Bit of Onion May Cause Harm

The scariest part of all this is just how little onion a chicken needs to eat before serious symptoms develop.

Even a few small bites of garlic could be enough to cause problems for your chicken, especially if it is eaten on a regular basis.

This means that even if you are feeding your chickens table scraps, you need to be very careful about what you include.

Studies suggest that eating even one-half of one percent of the chicken’s weight in onions can be enough to induce side effects.

It is always better to be safe and eliminate potentially harmful foods entirely rather than risk harm.

Can Chickens Eat Onion Raw?

No, chickens should not eat raw onions.

Can Chickens Eat Onion Cooked?

No. While cooked onions might not be as harmful, since some of the harmful compounds break down during cooking, not all of them will and they are still likely to cause problems.

Onions are unsafe for chickens in any form.

Never Feed Other Foods to Chickens that Have Been Prepared with Onions

Since we are on the topic of cooking, make it a point to never feed chickens anything that has been prepared with onions as an ingredient, even if it is something they could otherwise have to eat.

Also, your chickens should not be getting anything that has excess salt, sugar, oil, butter and the like.

The effects of onions can be bad enough on their own, but combined with these other harmful ingredients your birds might be facing a nasty one-two punch.

At best, extra calories will cause serious weight gain which is bad enough. At worst, those ingredients can lead to fatty liver hemorrhagic syndrome, salt poisoning, sour crop, hypertension and other ill effects.

Chickens can safely eat lots of things that people can, but they don’t need highly refined and fattening “people food.”

Baby Chicks are Especially Vulnerable to Onions

Baby chicks should never have onions.

They are even more vulnerable to the harmful compounds in onions, and their little bodies cannot handle the stress of dealing with them.

If you must give your chicks anything besides their starter feed (which should be their primary food source) make sure it does not contain onions or onion powder.

What Should You Do if Your Chickens Eat Onions?

If you think your chickens have eaten onions, the first thing you should do is keep a close eye on them for symptoms.

If they seem to be acting normally, then chances are they are fine and you don’t have anything to worry about.

However, if they start showing any of the symptoms listed above, take call your vet as soon as possible.

Onion toxicity can usually be treated if the bird did not ingest too much and you seek medical attention for them quickly enough.

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