The idea of ancestral diets is an interesting one for me. I hear it when people say they want to feed raw diets..."I want to feed a more ancestral diet" and "dogs and cats are carnivores", and I see it all over the marketing of pet foods, particularly grain-free foods. What does that mean to everyone?
In reality there are more than 260 mammal species listed under the order Carnivora. Yes, that list includes the cat and the dog, and closest taxonomic ancestors to both, the European wildcat and the wolf. However, it also includes otters, civets, seals, and bears. That last category is one of my very favorites to discuss in terms of comparative nutrition because it includes the Giant panda. Oh yes, indeed they are carnivores in every sense of the word. Anatomically they have short digestive tracts and limited ability to ferment fiber...surprised? The difference is that panda's have evolved and adapted to their environment and have lower requirements for protein and energy compared to other carnivorous species. If' you've ever seen panda poo, you've noticed that it looks just like panda food. They must consume gigantic amounts of bamboo just to meet those low energy and protein requirements (also why they don't move a whole lot). If I wanted to feed a panda like their other relatives (carnivores), I'd likely produce very fat pandas with metabolic issues. While we could feed pandas the same diets we feed other bears, we certainly do not...they are fed primarily bamboo as most of you already guessed. Why then do we constantly focus on wanting to feed dogs like wolves and cats like tigers?
When it comes to felids, I won't argue with anyone that chooses to feed a strictly raw meat or whole prey based diet. Cats have not evolved to be anything other than obligate carnivores. Their protein requirement is twice that of dogs and they require vitamins that are unique to the consumption of organ meats that other carnivores do not require in the same high concentrations (taurine, vitamins A, D, and niacin).