why won't my ducks lay eggs?
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Yeah, it was probably the move at first at least, ducks will typically stop laying for awhile after a stressful event (moving, predator attack, etc). Then there's also the fact that winter is coming and many ducks don't lay over the winter. Mine only lay in the Spring and Summer, then they all stop to go through their yearly moult, then winter is basically here and it gets super dark and they just don't lay anymore until spring. So that might happen with yours as well.
Scratch really isn't appropriate food for ducks anyway, maybe as an occasional treat if they like it. So I'd just stick to the layers pellets and offer the oyster shell on the side.