Quote:
Feed store personnel are notorious for giving bad advice. Of course if they don't have what you need they are going to try and sell you something else and tell you it's the same thing.
Grit and oyster shell are different.
If you're free ranging your chickens are probably finding plenty of small rocks and pebbles to use for grit.
Laying hens need oyster shell. The layer feed I use has calcium in it, but I offer them a little extra as insurance.
Edited to add: As an example - I moved my oyster shell and grit trays outside the other day when I was turning the shavings in the coop. I forgot about them and it rained hard overnight. The grit was fine, still hard as a rock (pardon the pun), but the oyster shell is now chalk.