The important things for this are limiting light exposure and lowering the protein in their diet. Khakis Campbells have been known to lay without a break for over a year. The feathers become worn and their physical health declines greatly.
Pen the ducks and Eliminate all light exposure. The first 24 hours withhold food & water. The following day give them water but no food. They will not be happy but remember that overlaying can be fatal. Day three start feeding oats or another feed that is below 10% protein. Feed them the low protein food and continue to keep them in the dark. By day 6 they should have stopped laying and their feathers should start dropping. Once they are no longer laying slowly increase the protein in their diet but don’t go over 14% until they are actively molting. At that point you can increase light exposure and protein content.
Reducing light exposure and protein in the diet is also helpful in treating a prolapse. Forcing a hen to stop laying allows her to heal more fully.
Diva Ducks 