Now, I HAVE had weanlings get into mom's Calf Manna before and THAT causes issues...nasty jelly poops that I had to work hard to cure. I will NEVER feed Calf Manna to weanlings
Right there is proof it can cause problems. The does just have a developed enough digestive tract you don't see the stress it may be causing. They've studied it more in horses but rabbits are quite similar and grain but especially corn causes gases and toxins from bacteria to be given off that stress the body since our grazing herbivores were never designed for grain in the first place. This is why laminitis happens in a horse. The toxins kill the laminae(little fibers that hold the hoof walls together) from the bacteria trying to digest the excess grain and corn being the worst offender. Rabbits just don't have hoofs and sensitive areas like that so your only clue comes from seeing digestive upset. Some grains can be fed safely like oats, barley, wheat, except in cases of allergies, but they still aren't really the ideal diet. They are just necessary because we push our animals beyond what their natural diet would allow them to handle for reproduction or exercise. Some grains/legumes like corn and occasionally soy products are not very safe or healthy and the fact you have to feed them in such a limited amount and to only certain animals is a red flag by itself.
