@MorganBieber,
What kind of ducks?
Hay is NOT the same as Straw.
Hay is cut to contain a high nitrogen (among other things) componant much of which is contained within the stem and tillers. (Tillers are the blades of grass that grow off the stem. This (the nitrogen) is what makes it valuable as stock feed, It is also th reason you shouldnt use it as bedding. It will compost in no time with a bit of duck poop and water mixed in.
Straw is the grass stem after the plant has dried out and the nutrient value within the stem has been drained out by the maturing of the seed head. Straw contains very few tillers and these contain almost no nutrient.
Best kind of bedding materials.
Wood shavings. You can often get this free from a cabinet maker or joinery or other factory making wood products.
Rice hulls from the processing of raw rice grains
Sawdust. get from a sawmill or other wood processing factory
Straw. Pea straw, wheat or oat straw
The main thing is not so much what you use but that you clean it out everyday. I'm not aware of any reason not to use straw for ducklings.
feed chick mix purchased from a pet store or rural supply store DO NOT FEED BREAD. Ensure CLEAN water is available. Clean water means change it every day and clean the water bowl.
These pets are YOUR responsibility Morgan. I'm trusting you to take good care of them.