Most places that sale horse feed sale cubes. The price varies and you can get it from 12.00 to 18.00 a 50 lb bag of cubes. That being said, my flock will not eat cubes wet or dry. They want the real thing, ie grass or turnip tops.
My horses eat cubes so do buy alot of them and always have them on hand. All the cubes the horses eat are wet and soften so easy to chew.
If you want to feed them alfafa suggest getting the ones for rabbits should be a much smaller size in pellet form. Also you can buy alfafa in a crumble/powder/dust form too at some feed stores.
Second cutting alfafa is great for leaves, those in the bale form, may perk up the interest of any poultry.
ML