Reply To: Opinion on vegan cats?

Cats are obligate carnivores: their physiology has evolved to efficiently process meat, and they have difficulty digesting plant matter. In contrast to omnivores such as rats, which only require about 4% protein in their diet, about 20% of a cat’s diet must be protein.
Obligate means by necessity. Merriam-Webster.com defines obligate as “biologically essential for survival.”
Obligate + carnivore = cats must eat meat to survive. This is because the protein in animal tissue has a complete amino acid profile. Amino acids are the building blocks of protein. Plant proteins do NOT contain all the amino acids critical for the health of obligate carnivores, and unlike humans who have the physiological ability to turn plant proteins into the missing pieces needed for a complete amino acid profile, cats don’t have that capacity.

One of the amino acids missing in plants is taurine, which is found in animal muscle meat, in particular the heart and liver. Taurine deficiency causes serious health problems in cats, including cardiovascular disease and blindness. Some cat owners believe they can feed their pet a vegetarian or vegan diet, and add a taurine supplement. In my opinion, this is the equivalent of eating nothing but iceberg lettuce and taking a synthetic multivitamin. That vitamin can’t possibly make up for all the nutrients missing from an iceberg lettuce-only diet.

The quality of the protein you feed your cat is also important. The biological value (BV) of a protein measures the bioavailability of its amino acid content. Better quality proteins have higher biological values, meaning they are easier for the body to digest, absorb, and use properly. Proteins from animal muscle meats typically have high BVs, whereas proteins from snouts, beaks, feet and tails have zero biological value because they are wholly indigestible.

Cat owners also need to avoid non-meat sources of protein, for example, soy and corn, as these are not species-appropriate foods for kitties.

Remember: It’s not just the amount of protein that’s important – it’s also the source (for carnivores it should be animal vs. plant-based) and bioavailability (fresh, unprocessed, preferably raw muscle and organ meat is ideal for healthy cats and dogs).
Information – healthypets.mercola.com