I wonder if there might be a high calorie leaf forage that would be good.
I would think most grains would be good.
We discovered 'duckweed' or lemna-which is an abundant pond plant- is excellent chicken feed. A fishing net frame with an old sheer curtain loosely fastened across makes a great skimmer and in 15 minutes or less it is possible to gather several 5 gallon pails of greens and the bonus are the snails which inevitably are in abundance in the mix. Duckweed has the protein equivalent of soybeans and higher carbohydrate content than corn so the birds thrived on it. We fed it to both the laying hens and the broilers with great results. In fact, they ate it with great delight. Duckweed does well in water that is high in nutrients and is able to take many of the micronutrients from the water and make them available in a very digestible form. Great article on this at this link: www.fao.org/ag/againfo/resources/documents/DW/Dw2.htm