It is for the extra nutrients. It's made so that kittens that are too young to wean can survive on that alone.
Ferrets: Contessa, Frankenfurter, Butterscotch. Kitties: Watson, Oskar DIP Sinnead, Vincent, Boris, Zeus and Athena, Willow, Mr. Frodo, Indie, Lucrezia, Judge, Odin, Miss Emily, Suki, Cody, Aristotle. RIP Herne, Ligeia, and Mr. Stubbs