Soaked alfalfa pellets or alfalfa meal might work better. Sometimes the cubes have a lot of short, coarse, stemmy stuff in them, don't know how good that would be for them. I would just soak in water, not milk, since chickens cannot digest milk.
If chickens live in an environement where they are always around the hay and occasionally sample a little that's fine. If they are not and you are talking about just tossing a bit into their coop/run now and then they may eat to much of it and risk crop impaction. Timothy and other grass hays...