Transforming vegan food externally for absorption by cats (and their digestive system)

Question

This post may well be better suited for the biology or medical sciences Stack Exchange.

For safety, and, also, because, there may be more dieticians on this site, if, they may be helpful (perhaps or maybe, not, but maybe yes), but, especially, because, this post may be better suited here, sorry.

I am trying to construct an external biological digestor for cats. This, would be, an animal, that processes some vegan food (or, at the most, vegetarian), and turns it into the lowest common denominator of broken down elements that both the cat (normally, not vegetarian), can digest, with, success, and producing vitality, for the cat, and the food is not delivered from a carcass.

How, can I construct, such a food generator.

I repeat, the generator, biological or otherwise, takes some vegan food that the cat cannot process, breaks it down (like, an external stomach), into food that the cat's internal digestive system can digest, with benefits, for the cat, and the broken down food is fed into the cat (bypassing the cat's stomach).

Why, is this possible, (or, if not, then why not)?

Thank you.

Answer 1

As carnivores, cats are evolved to subsist mostly on animal proteins and fats. Unlike herbivores, their digestive systems do not have the ability to digest the polysaccharide carbohydrates (cellulose and starch) that make up the bulk of plant-based foods. An external digester would seem to get around this problem by digesting the carbohydrates for the cat.

However, cats are adapted to animal-based diets not only in terms of their digestive systems but also in terms of their metabolisms (how their cells use nutrients after they are digested). The basic components of polysaccharide carbohydrates are sugars, and cats are not adapted to metabolize large amounts of sugars. Cats that consume too much sugar are likely to develop obesity and diabetes [1].

You could potentially get around the problem of carbohydrates by using processing methods similar to those used to produce imitation-meat products like Beyond Meat. This involves industrially extracting protein from soy or other legumes, and adding saturated fats such as coconut oil. For details on the extraction process of protein from soy, see this article.

However, there are still problems with feeding cats plant-based proteins. Certain essential amino acids, specifically arginine and taurine, are absent or only present in low amounts in plant-based proteins. Some vitamins, such as vitamins A and B12, aren't available from plants. Cats that do not get these nutrients may experience many health issues [2]. These nutrients would have to be added to the processed plant-based food, either from animals or chemically synthesized.

Even if this were all possible, which would require millions in research and development, we still don't know if cats would be healthy eating these processed plant-based foods. There might be essential nutrients we don't know to add, or harmful compounds in the plants that we don't know to remove. With our current technology, animal meat is a necessary part of ethically keeping cats.