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Can Spinach Cause Chickens and Ducks to Lay Soft-Shelled Eggs?

Feeding too much spinach and other foods containing oxalic acid can lead to soft-shelled eggs in backyard chickens and ducks, but that doesn't mean that spinach can't be a part of their healthy diet.

Ducks love spinach.

Or rather, I should say ducks love pretty much anything green, especially if you float it in a tub of water!

But truthfully, ducks do love spinach, as do chickens.

But I had been somewhat hesitant to give too much because spinach  to my flock because spinach frequently appears on the list of foods to avoid.

And that confused me. Because as far as I knew, spinach was super nutritious.

The Benefits of Feeding Spinach to Chickens and Ducks

Spinach is high in calcium and other nutrients (along with collards, kale, chards and Brussels sprouts), so I really wanted to find out if spinach could be a healthy part of my ducks’ diet. So I knew I needed to do a little bit of research to answer my questions.

Can Spinach Cause Chickens and Ducks to Lay Soft-Shelled Eggs?

I knew the warnings I had read about feeding spinach to chickens and ducks had something to do with the oxalic acid in the spinach (as well as in chard and beet greens), but didn’t know any details.

So I did what every good chicken keeper does when they have a question about the health of their flock: I called my Mom.

No, my  mom doesn’t raise chickens now, but she did grow up on a chicken farm and she's also a nurse who is really into eating healthy and knows all about food synergy (how certain foods interact with each other in your body), so I do take what she tells me in many cases and apply it to our chicken keeping.

Spinach and Oxalic Acid

I explained to her my dilemma and she told me that the oxalic acid in spinach binds with calcium and prevents our body from being able to absorb the calcium as well as it should.

Of course in egg-laying chickens and ducks, that’s the last thing you want since eggshells are comprised nearly entirely of calcium. If they don't get enough calcium, that can lead to soft-shelled eggs that break easily or even can get stuck and cause egg binding in a laying chicken or duck.

Adequate calcium is also needed for the birds perform the contractions that push the eggs down the oviduct. So inadequate calcium absorption is a pretty big deal for egg-laying birds.

Apple Cider Vinegar and Calcium Absorption

My mom went on to tell me that by adding a splash of apple cider vinegar to a spinach salad, the stomach acids are increased, which helps with absorption of not only calcium but other minerals and nutrients.

Low stomach acid prevents proper absorption, so the acetic acid in the ACV raises the stomach acids and boosts absorption.

Perfect! I already add apple cider vinegar to our flock's water a few times a week for an immune system booster and to help keep the water bacteria- and algae-free.

So it is true that too much spinach can cause chickens and ducks to lay soft-shelled eggs, but now when I toss my chickens and ducks some spinach, I make sure that's on the same day I am adding the apple cider vinegar to their water.  

(In the duck's case, both the apple cider vinegar and spinach go right into a tub of water.)

Because I had figured out the reasons why spinach can cause soft-shelled eggs, I feel comfortable adding some spinach, chard and beet greens to our ducks’ diet in moderate amounts as long as I add a splash of apple cider vinegar to their water at the same time.

And if I do ever find a soft-shelled egg, I'll cut back on the treats for awhile.

Note: I did confirm my Mom’s information with a few other reputable sources and sure enough she was right (aren’t Moms always?), and the way the oxalic acid and apple cider vinegar works in a human body does apply to ducks and chickens as well.

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