Cats are obligate or hypercarnivores, this means they are almost exclusively reliant on animal prey to meet their nutritional needs, while we may think of hypercarnivores being the larger species of cats such as Lions, Tigers and leopards our small house cats are no different in their need of an animal-based diet.
What helps us understand that our feline companions require a diet that should be almost exclusively animal based?
Dentition is that of a true carnivore, they have large canines for griping and holding prey and sharp molars designed to shear through flesh and bones, they lack the ability to move their jaw from side to side to grind plant matter like a herbivore with flat grinding molars.
Taurine is an amino acid that was discovered in the 1970’s to be essential to feline health, after many cats developed dilated cardiomyopathy and retinal degeneration after consuming ultra-processed feed that lacked Taurine due to the processing methods needed to cook the food, as Taurine is generally only found in animal based foods it was mandated that all cat food had to be supplemented with Taurine (often in synthetic form), while this is essential for ultra-processed food, fresh raw meat based diets contain Taurine in adequate to plentiful amounts to avoid a deficiency. Other carnivores such as dogs are able to make their own Taurine converting Cysteine and Methionine two other essential amino acids, cats are unable to convert their own taurine efficiently so must rely on it coming directly from their diet in a pre-formed state.
Amylase produced in the pancreas needed for the digestion of starches is limited in cats compared to another animals, as such a cats natural energy source is from proteins via gluconeogenesis and fats.
Retinol (Vitamin A) is required preformed in the diet as cats do not have the ability to convert carotenoids the pre-cursors to vitamin A, Retinol is only found in animal-based foods.
Arginine is an amino acid that is required in higher amounts in cats compared to other animals, just a single arginine free meal can cause some cats to develop hyperammonemia (high levels of ammonia in the body).
Arachidonic Acid an essential omega 6 fatty acid is required by cats who cannot convert their own from Linoleic acid, this is only sourced from animal meats and fats.
Cats also function is a constant state of Gluconeogenesis where they convert glucose for energy from protein. Cats are unable to downregulate gluconeogenesis even in protein is deficient in the diet.
Cats lack a nutritional need for carbohydrates and can struggle to tolerate high carbohydrate diets, when carbohydrates are fed this puts pressure on the pancreas to produce insulin and over time can lead to Diabetes Meletus.
Putting all of the factors into consideration it is clear that cats require a diet that is high in meat proteins and very low in carbohydrates and plant matter to meet their unique nutritional needs.
References:
1. Nutritional Uniqueness of the cat: https://www.tandfonline.com/doi/pdf/10.1080/01652176.1998.10807428#:~:text=Cats%20appear%20to%20be%20in,protein%20and%20low%20in%20carbohydrate.
4. Nutrient Requirements of Dogs and Cats, National Research Council, 2006 publication.