Found your previous post, you may have gotten this from the original thread info but it's not leavening, yeast, or fermentation that is forbidden -- it's products made from grains that have the potential to leaven (that have been exposed to water for more than 18 minutes before baking). Matzah...
We are a long ways away from next pesach (Shana tovah, everyone!) but I've been thinking about this ahead of time. For waterfowl (ducks and geese), do you think a mix of cracked corn, sorghum, soybean meal, and fish meal would be ok?