Interesting observation about calcium post-processing

[humblehillsfarm]

I’ve been feeding free-choice calcium along with an all flock feed for some time. We’ve all read extra calcium can be bad, and the general assumption is chickens eat it when they need it.

We processed some 16 week old cockerels a couple of weeks ago and the gizzard of every one of them was packed with oyster shells! I had observed them chomping on the oyster shells numerous times, but the proof is in the pudding, or gizzard.

It actually made me feel better about feeding layer feed to my girls. I might switch to a high protein layer during the summer. My local Southern States sells a 20% “hearty hen” feed.

What do you all think?

 

[nuthatched]

That's a really interesting discovery! The only reason I can think of is maybe the calcium in feed is more easily absorbed and the shell isn't? I don't know, I know my fool rooster would eat oyster shell, I figured he needed it.

 

[humblehillsfarm]

That's a really interesting discovery! The only reason I can think of is maybe the calcium in feed is more easily absorbed and the shell isn't? I don't know, I know my fool rooster would eat oyster shell, I figured he needed it.

I was also thinking calcium in feed could be more easily absorbed. I often mix in egg shells and I didn’t see any in the gizzard, and the general consensus seeks to be that is quickly absorbed too. So maybe oyster shell, being slow to break down, isn’t so harmful? There was a good 6-10 largish pieces inside every crop. Very little pebbles.

 

[3KillerBs]

Every member of my flock has sampled the oystershell, but only the layers eat it consistently.

 

[aart]

Was there any grit in the gizzard?
Wondering if they were gorging on the oyster shell in lieu of granite grit not being available?

I slaughtered an old hen whose gizzard was packed with grit.
That's when I stopped offering grit in a feeder and started sprinkling it around with the scratch ration.

Excessive calcium takes long time to adversely affect the health of a bird that doesn't need it.

 

[ladybrasa]

I also added some oyster shell for a mixed group of various age young ones, then later processed some cockerels. 3-4 months I think. They all had the oyster shell in their gizzard too, in addition to grit.

 

[humblehillsfarm]

Was there any grit in the gizzard?
Wondering if they were gorging on the oyster shell in lieu of granite grit not being available?

I slaughtered an old hen whose gizzard was packed with grit.
That's when I stopped offering grit in a feeder and started sprinkling it around with the scratch ration.

Excessive calcium takes long time to adversely affect the health of a bird that doesn't need it.

There were stones here and there, but less than the oyster shell. The birds all free range. When we processed some cornish cross last year, they obviously weren't given any calcium but we did attempt to "free range" them. The "free ranging" was them leaving the coop and waddling over to the feeder which I placed as far from the door as possible lol. Anyways, they were chocked full of pebbles, which was mildly surprising. I guess I didn't realize how much natural instinct was still present in cornish cross. Anyways, my point in mentioning the CX was that they had access to the same dirt as the cockerels, and they managed to find suitable pebbles.

 

[humblehillsfarm]

I also added some oyster shell for a mixed group of various age young ones, then later processed some cockerels. 3-4 months I think. They all had the oyster shell in their gizzard too, in addition to grit.

Oh, and we don't have anything close to granite unfortunately. We have nothing but coal and sandstone. I've never put out grit for the mature flock since they free range, but maybe I should since granite would, in theory, stand up to the test of time more than sandstone?

 

[K0k0shka]

Oh, and we don't have anything close to granite unfortunately. We have nothing but coal and sandstone. I've never put out grit for the mature flock since they free range, but maybe I should since granite would, in theory, stand up to the test of time more than sandstone?

Sounds like they need grit, can't find any, and are substituting with whatever they can find.

Also, growing cockerels need calcium for growing bones, just like any other growing boned animal has higher calcium needs than the maintenance level needs of a full grown adult. After they mature, non-laying birds' needs drop.

And a third possible explanation. Oyster shell is less natural and intuitive to chickens, because they wouldn't normally encounter oysters in their daily lives. So juvenile birds may not be familiar with it, and eat it thinking it's something else (grit, feed, etc.) Egg shells, however, are very familiar to an animal whose species lays eggs, so they know what to do with them. Chickens prefer egg shells over oyster shell for calcium if given the choice, for that reason, but people often use oyster because it's quick and convenient (they don't have to bother collecting egg shells etc.)

 

[rosemarythyme]

I've never put out grit for the mature flock since they free range, but maybe I should since granite would, in theory, stand up to the test of time more than sandstone?

Granite is harder, sharper and longer lasting (as grit) than sandstone, so yes that's why it's the preferred grit material, at least in the US.

For the low cost and the fact that it lasts forever (no expiry date as it's just rock) I think keeping a bag of grit on hand is a worthwhile investment.