Any brand of laying feed contains extra calcium and oyster shell shouldn't really be needed. Laying feed shouldn't be started until the pullets have started laying, the laying feed doesn't make them lay, it just provides the extra calcium needed for strong egg shells. If your worried about your rooster getting too much, switch to a high protein "all-flock" feed. Then you can supply the hens extra calcium by oyster shell in a seperate feeder or even scatter it around their pen or where they forage. I bought a 50lb bag of OS a few years ago and still have most of it. All my birds free range from the time the sun comes up till it sets, and other than in January, their shells are nearly "bullet proof". In Jan, I may throw a few cups of it on the pen floor if the shells begin to get a little easy to crack.I’m not sure if the Dumor layer feed or not. My hens wasn’t laying at the time when I bought it. I do know it’s the 2nd stage feed for their age group and it crumbled. I don’t have to bag anymore to know for sure. I do remember the girl told me when they started laying I should get them some oyster shells to mix in the feed to give them calcium. That’s why I’m thinking it’s not the Dumor layer feed. That’s why I mix it with the other.