An obligate carnivore is an animal that must eat the tissue of other animals in order to thrive, according to its genetic makeup. Obligate carnivores may eat other foods, such as vegetables, grains or fruit, but they have to eat meat as the main source of their nutrients. Meat includes but is not limited to beef, chicken, lamb, turkey and fish.
However, not all carnivores are obligate (obligatory) carnivores.
Definition of Carnivores
Any of various generally meat-eating mammals of the order Carnivora. Carnivores have large, sharp canine teeth and large brains, and the musculoskeletal structure of their forelimbs permits great flexibility for springing at prey. Many carnivores remain in and defend a single territory, such as dogs, cats, bears, weasels, raccoons, and hyenas. Great white sharks and (according to some classifications) seals and walruses are all carnivores. Some birds are carnivores, including seagulls and eagles.
Not all Carnivores are Obligate Carnivores
However, not all members of the order Carnivora are obligate (obligatory) carnivores.The difference? Take bears, for example. While bears kill and eat flesh, most of their species are omnivorous (eating both animal flesh and plant material). Humans are omnivorous; so are dogs. Omnivores can live quite well on a combination of both meat and plant foods.
Our intestinal tracts are quite long and can do a satisfactory job of digesting and extracting the nutrients we need, including protein from legumes, rice and some vegetables, and eliminating the rest as waste.
Why Are Cats Obligate Carnivores?
Cats "guts" are much shorter than ours. They do not have the ability to fully digest and utilize the nutrients in plant material.
Although theoretically, they might get enough protein from plant material to exist, they need taurine in order to thrive. Taurine is found primarily in the muscle meat of animals and is most highly concentrated in the heart and liver.
In the wild, cats may get a small amount of grain and other plant material from the stomachs of their prey, but our domesticated cats really do not need large amounts of grain. Corn is a good example. It is a cheap source of protein, and many of the supermarket brands of dry cat food are packed with corn in various forms, e.g., corn bran, corn germ meal, ground corn, corn gluten, corn gluten meal. Avoid any cat food containing corn, especially listed at or toward the top of the ingredients. (Pet food ingredients are generally listed in descending order by dry weight.)
It should also be noted that some manufacturers practice "splitting" to keep corn from the very top of the list. Splitting involves carefully calculating the percentage of each kind of corn so that the aggregate total weighs more than any other ingredient, however, none of the corn ingredients is listed at the very top. There is nothing illegal about this practice, but it puts the consumer at a disadvantage.
It would be much more transparent if manufacturers were required to list the percentage by weight of each ingredient. Corn is not only a poor source of protein, it is also a known allergen for some cats.
While some cat food manufacturers add small amounts of vegetables and fruits to their formulas, the premium foods always have named meat protein high on the list of ingredients. The fruits and vegetables are generally added for their vitamin and mineral content, and sometimes for their probiotic value.
Vegetarian Cat Food
Some vegetarian humans prefer not to handle meat in any form and purchase commercial vegetarian foods for their cats. Although these foods meet the AAFCO nutritional standards for a "complete and balanced diet," they have come by it artificially. For some, this is much like using bleached flour for white bread, then adding back the nutrients one would get naturally from a good, whole-grain bread.
How can you be sure you've added back all the nutrients? While cats need a meat diet to thrive, learn more whether you should try a vegan diet for your cats.