I always have given my mares a nice warm bran mash after foaling and starting in minis in 1985 until this day, I give my entire barn a warm bran mash meal once a week instead of their grain meal.
For a recipe, I just mix the bran with warm water until it is soupy, add molasses and a tablespoon of mineral oil for each horse , mix well and dish out to them. They love it and look forward to Sat. nights. BTW. my Vet approves and it was Tufts University that told me to do this in the first place after my first colic that had to go there. But I don't advise you to do it unless your Vet approves.
Joyce