California Naturals may have been adding sand to "bulk up" the food without adding cost. Sand (depending on where they get it) is free - they can still claim a bag of food is 30#, but might only have 20# of ingredients, cutting cost.
Re:K/D: While Hobbes and Spike are cats: I was feeding them K/D as Spike has early kidney disease. Hobbes is 15 and taking prednesone for Asthma, so feeding it to her as well certainly wouldn't hurt. Neither cat likes the canned K/d and refused to eat it. They both ate the k/d kibble, but when Spike started loosing weight and the kibble was falling out of his mouth - he is 22 and is missing a lot of teeth due to age - when the bag ran out I got Pirina One Vibrant maturity from the store as I had been adding glucosame/chondroitin as they both have arthritis. Spike gained weight. Not a lot but the musces on either side of his backbone that had started to atrophy filled back in. Spike will never be a normal weight, but I want to keep as much weight on him as I can.
I think it was kibble shape, rather than any ingredient - the K/d kibble fell out of his mouth because it is round (cylinder) shaped, and fell out too easy, the Purina One was more flat little triangles that stayed on his tongue better. There is no more kibbler all around the dish so it is going down into his stomach rather than ending up on the floor.