Well, here are the ingredients for Farmgate, which is a common layers pellet.
Wheat, Wheatfeed, Calcium Carbonate, Sunflower Ext, Soya Bean Ext,
Oats, Vegetable Oils, Di Calcium Phosphate, Salt, Sodium Bicarbonate,
Wheatfeed is apparently a by product of flour milling, so bran, seed coat and some flour.
Dicalcium phosphate is added to toothpaste, cereal, dog treats, enriched flour and so on, to add calcium.
Sodium bicarbonate is baking soda
Methionine is an amino acid found in pretty well all proteins we digest.
So I can't honestly see anything there that is harmful to either sheep, goats or dogs.