Battery hens are debeaked with a hot machine blade once and often twice during their lives, typically at one day old and again at seven weeks old, because a young beak will often grow back. Debeaking causes severe, chronic pain and suffering which researchers compare to human phantom limb and stump pain. Between the horn and bone of the beak is a thick layer of highly sensitive tissue. The hot blade cuts through this sensitive tissue impairing the hen's ability to eat, drink, wipe her beak, and preen normally. Rennet is derived from the stomach linings of calves.
Rennet is used to make cheese.
These substitutes can be either from vegetable sources, or may be created in a lab. Vegetable rennet is usually called 'rennin' to distinguish it from the animal-derived type. Some soy cheeses contain cassein which is a milk-product. Dairy cows are made pregnant yearly to ensure they produce adequate milk. In nature the calf would suckle for almost a year but nature, like the calf, is denied by the dairy industry.