I know your not suppose to make fast changes to a horses diet, so why of all days would you give a mare bran mash (something new to their diet) right after foaling? Bran does not "clean" a horse from the amount of fiber in it, like it does for people, horses get more fiber in a day from a regular amount of hay and grazing than bran will ever give them. It "cleans" them out because it is a change to diet and it causes a mild digestive upset. Mind you this is what my vet(s) and a nutritionist from Purina told me, and it is a major miss conception, sort of like not giving a horse water after a work out because it will get sick. That and the wheat bran is pretty much useless for horses, at least rice bran has oils and higher fats to help gain weight.