Small Pet Select Flaked Oyster Shell-Calcium Supplement for

The Verdict

If you keep backyard chickens, you already know the sinking feeling of collecting a thin-shelled egg. That’s the exact problem Small Pet Select’s Flaked Oyster Shell Calcium targets — and based on 220 Amazon ratings averaging 4.4 stars, it’s solving it for a lot of flock owners.

What you actually get

The 5-pound bag contains 100% flaked oyster shell — no fillers, no synthetic additives, no artificial coloring. As shown in the product image, it’s a natural tan and white flake mix that looks like what you’d expect from crushed marine shells. The flaked (not powdered) texture is the key differentiator here. Powdered calcium tends to settle at the bottom of feeders and get ignored; flakes stay mixed in with feed and remain accessible.

Performance and real-world use

The science here is straightforward: laying hens need roughly 4-5 grams of calcium daily, and most commercial layer feeds only provide about half that. Oyster shell calcium carbonate fills the gap. What makes Small Pet Select’s version stand out is the particle size. It’s large enough that hens recognize it as a separate supplement (which they’ll self-regulate), but small enough that it doesn’t require grit to break down.

The flaked form also means less waste. One reviewer noted, “My hens were leaving the powdered stuff I tried before, but they actually peck at this. I’ve seen noticeably harder shells within two weeks.” That tracks with what avian veterinarians recommend: offering calcium free-choice alongside feed, not mixed in, so birds can self-medicate based on their laying cycle.

What buyers consistently praise

The recurring theme in positive reviews is shell quality improvement. Multiple buyers report “thicker shells” and “no more soft eggs” within 10-14 days of consistent use. Several mention it’s the only calcium supplement their picky hens will actually eat — likely due to the flake size and natural oyster flavor.

Duck owners also report success. One reviewer wrote, “My Muscovy ducks go through this quickly, but their eggs are noticeably stronger. Worth every penny.” The lack of added phosphorus is another point buyers appreciate — too much phosphorus can actually inhibit calcium absorption, so a pure calcium carbonate source is the safer choice.

Where it falls short

The flaked texture has a downside: bantams and younger pullets sometimes struggle with the larger particle size. If you have smaller breeds, you may need to crush it slightly or mix it into wet feed to get them started. A few reviewers noted their birds ignored it entirely for the first week.

There’s also no measuring scoop in the bag. You’ll need your own tablespoon or cup for consistent feeding. And while the bag is resealable, shipping agitation creates some dust at the bottom — not a quality issue, but worth knowing.

Who should buy this

• Backyard chicken keepers with laying hens experiencing thin or soft shells
• Duck and goose owners needing a pure calcium source without phosphorus
• Small flock owners (5-15 birds) who want a 5-pound bag that lasts 2-3 months
• Anyone using a complete layer feed who wants to offer supplemental calcium free-choice

Skip it if you have only bantams or young pullets that may reject the flake size, or if you’re looking for a calcium supplement with added Vitamin D3 (this is pure calcium carbonate only).

FAQ

Q: How much should I feed? Offer free-choice in a separate feeder — hens will self-regulate. A good starting point is 1 tablespoon per 4-5 birds daily, but don’t be alarmed if they eat more during peak laying.

Q: Can I mix it into their feed? You can, but free-choice is better. Hens need more calcium when actively laying and less when molting or broody. Mixing forces a one-size-fits-all dose.

Q: Is this safe for ducks and geese? Yes. The flake size works well for waterfowl, and several reviewers specifically use it for ducks. Just ensure fresh water is always available.

The Verdict: 4.2/5

Buy it if you want a no-fuss, pure calcium supplement that hens actually eat and that delivers visible shell improvement within two weeks. Skip it if you have only tiny breeds or prefer a pelletized calcium that mixes more seamlessly into feed.

At 4.4 stars from 220 ratings, this is the kind of product that does exactly what it claims — no more, no less. It’s not flashy, but your hens’ eggshells will tell the story.

Where to Buy

👉 Check Price on Amazon →

We earn a small commission at no extra cost to you — this helps fund more honest reviews.

Last updated: 2026-08-06. Ratings and prices current as of review date. Verify on Amazon before purchasing.