Animals are not ours to eat, wear, experiment on, use for entertainment, or abuse in any other way.

Do ingredients of synthetic or plant origin work as well as their animal-derived counterparts?

Remember, animal ingredients are used because they are generally cheaper, not because they are better than vegetable-derived or synthetic ingredients. Today’s slaughterhouses must dispose of the byproducts of the slaughter of billions of animals every year and have found an easy and profitable solution in selling them to food and cosmetics manufacturers.
 
Furthermore, rendering plants process the bodies of millions of tons of dead animals every year, transforming decaying flesh and bones into profitable animal ingredients. Slaughterhouses, which provide the inedible parts of animals killed for food, are the primary sources of rendered animals, but the bodies of dogs and cats who are euthanized in animal shelters wind up at rendering plants too.