When to start oyster shell

[superchemicalgirl]

My girls are 15 weeks old. Some of them are developing the big red combs and wattles but most are not.

As most are "dual purpose" heavy birds they are currently eating a 20% protein pellet diet plus some free ranging time and snacks from me. I plan on adding crushed oyster shells and crushed egg shells as free choice when they need it.

Question is: when do they need it? It seems a bit silly to me to wait until they start laying to add it - doesn't laying create a huge flux of calcium from the body? Wouldn't I want to get ahead of that and offer the calcium right before they start laying?

If I put it out now will they know to get it only when they need it?

The most developed is a white leghorn:

 

[dee88]

I, too, have 5 pullets that are about 15 wks. old and I bought oyster shell last week but after reading bag, it says start @ 20 weeks. I'm with you, it seems we should start them now so they will build up calcium. I think I'm going to give them some now in a bowl. I don't think it will hurt anything!

 

[cafarmgirl]

I started putting out oyster shell for my hens just before they started laying, when their combs were getting red. Must have been about 16 or 17 weeks. I figured it was better to make sure they had what they needed before they started laying.

 

[Boo-Boo's Mama]

I put oyster shell out after the first egg which had a very hard shell (must be all the yogurt I have given them over their short life). I have it in a tuna can screwed to the post by the feeder...they help themselves as they need it...in fact today I saw BO's and BR's eating it and they are not laying yet...BR's are getting the red faces.