By no means a ‘waste’ material, it adds to the balance of nutrition in dog foods.
By-products is not a ‘dirty’ word for waste, but a description of often valuable nutritious materials that people choose not to eat, and have therefore removed from food stuffs. These food stuffs in their refined state, then become the primary food product in the food chain. Animals, and in particular pets, benefit enormously from the wastefulness of man.