There are a bunch of ways we all try to do right by laying ducks and drakes. I am currently making some compromises. I had read that with laying ducks, and drakes, best to use non-layer feed with oyster shell on the side. And in my perfect world, we would be all set.
Except Romy, and sometimes some runners, don't work that way. I have to pop up the calcium quite a bit when they are laying. No problem until . . . . drum-roll - - - the arrival of Bean, our first and only drake.
After consultation with my wonderful vet, we agreed that for a number of reasons, Bean will be eating more layer feed than ideal. Right now he is kept with his two buff girls in side by side pens because of his obsession for Romy.... long story.... so that group gets mostly Mazuri maintenance, with a little layer, and oyster shell on the side. Both girls are laying just fine, and they have quite an appetite for oyster shell!
The rest of the flock gets layer pellets, oyster shell, calcium gluconate three times a week in their water, and Romy gets special treats with prescription Neocalglucon. Oh, yeah. Simple life.
So, I hope some of this gives you ideas on how you want to work it with your duckies.