As with lists for enumerating poisonous plants regarding poultry, always best taken with a pinch of salt because many medicinal plants make it onto the list too, often without any deaths proven to their names. There is plenty of old information detailing their uses to treat common farm ailments, which though skeptical on average I have tested whenever confronted with a disease, and found holds true.
Ivy (Hedera Helix) is an old birth-aid and internal cleanser. Was used in treatment of Dropsy, fevers, retained afterbirth, etc. Just a few leaves were the prescribed dose for a sheep sized animal, like you mentioned your animals ate. It strengthens the reproductive system. But there are several types and one is toxic.
St John's Wort (Hypericum Perforatum) is also a potent medicine, was used for Hodgkin's disease, Dropsy, rheumatic issues and wounds, worms, and in Germany doctors still prescribe it as an antidepressant to humans, because asides from the photosensitivity it doesn't have the side effects other antidepressants do. It's sold for human consumption in many countries even though most people don't know what it is or how to use it.
As always, too much of any good thing is fatal. Can't have too much oxygen, water, or whatever.