Spoiled/Soured Milk for Fermenting Feeds

Hello all! I was curious if I could use soured milk for fermenting feed or if this is not a good idea. I am very excited to get to try fermenting feed and had some soured milk in the fridge for making bread with and thought that it might be worth a try. My older doctor had used to give his children soured goats milk, so I don't think that it would be bad and someone had even suggested to me to let it curdle and then feed it to the chickens like that for health benefits.
Thanks!