Bovine gelatin and bovine collagen are both made from the bones and skin of cows, and they are both health-boosting products that you can add to smoothies and fruit bowls to help with bone and joint pain, gut healing, and even younger-looking skin. As they are used in this book, they can be used interchangeably. The only difference is that in bovine collagen powder, the proteins are broken down into smaller pieces, so it is even easier to digest. Also, bovine collagen powder dissolves more easily in cold liquid and does not have a gelling effect. Otherwise, they are pretty much interchangeable unless you actually want the gelling effect. I use both of them, but if you only want to spring for one of them, I would pick the bovine collagen powder, which you should be able to find in health food stores or online.