I don't think ducks vs. chickens would make it much harder or easier.Is it easier to grow your own duck feed or grow your own chicken feed? I don't have a ton of land to work with but not super small. I am trying to decide whether I want ducks or chickens, I don't have either. I live in a subtropical climate. Thanks!
I know more about chickens than about ducks, so I will mostly use them as examples for the rest of my post.
At a minimum, you would need to provide:
--enough energy (calories) per day. For an adult hen, this takes about 1/4 pound of commercial chicken food per day, or about 100 pounds per hen per year. Commercial chicken food is dry, made mostly of grain, and low in fiber. If you are feeding foods that contain water, or that contain more fiber, your birds will have need more pounds to get the same number of energy (calories).
--enough protein, including the correct mix of amino acids. Things like meat and fish usually have amino acids in a workable balance, but most plant sources are deficient in certain ones. This can get complicated, and I don't personally know enough details to say much more. Birds that are growing, molting, or laying eggs will need more protein than birds that are not. For example, a laying hen needs enough protein to make one egg in addition to the protein her body needs to stay healthy each day.
--the right amounts of vitamins and minerals. I know they need plenty of calcium but not too much, so providing it free-choice is a good way to let them choose the right amount. For the other vitamins and minerals, different ones are found in different foods, and I don't know enough to help with specific details.
Just checking whether you can produce enough calories might be a good starting point.
A google search tells me that many commercial chicken foods have about 1500 calories per pound. So if a hen were eating 100 pounds of them per year, she would be eating 150,000 calories per year. If your property cannot produce that many calories per year per hen, you will need to buy in food of some kind or another. If you can produce that many calories but they do not have the right balance of nutrients, you will still need to buy some things as supplements.
One thing that works well for many people:I was truly hoping but honestly I wondered if it would take too much room. Perhaps the best I can do is supplement.
provide a feeder of a complete commercial feed free choice, and also provide free range and the things you grow. That way the chickens can fall back on the commercial feed if needed, and you don't have to do as much planning and ration-balancing.
Things like grass do not have many calories (mostly water and fiber), so your chickens might eat a surprisingly large amount of green plants without much change in how much commercial feed they need.