what is collagen peptides made of?

As a brand owner, the most important thing I have to explain to my customers about what collagen is made of is what it is not made of: plants.
There is no such thing as vegan collagen. Since collagen is exclusively an animal protein, true collagen peptides are always 100% animal-derived. When we get customers looking for vegan alternatives, we have to pivot and sell them “collagen builders” (which are made of plant-based vitamins and amino acids), but the peptides themselves are strictly sourced from animals.