How do centaurs get enough calories to live?

Question

This is a partner question to How do centaurs get enough oxygen to run

Centaurs are a common mythological figure, with the body of a man where a horses head would be. They usual exist in a fantasy world but lets say they are not sustained by magic but instead by biological processes.

This has obvious advantages in terms of speed, maneuverability, visibility, etc. There is however one obvious problem, they have the small mouth and throat of a human trying to support the energy and oxygen requirements of the massive body of both a human and a horse.

Humans are not adapted to eat grass or grains, however a centaur could potentially have a horse's digestive system so would centaurs be able to live on grass? If they could would they be able to graze? It seems their body shape would be more suited to giraffe-like eating fruit and leaves from trees rather than grazing of grass.

Could they get enough energy that way though given their smaller mouth? Would they need to be carnivorous or at least omnivorous?

Answer 1

A 1000 pound horse needs approximately 15,000 calories a day for maintenance, the average 160 lb human needs around 1800. Take 70% of a horse and 50% of a human, that gives you about 11,400 calories per day as a maintenance level. (Pretty much just breathing in and out).

A typical McDonald's meal (Quarter pounder, fries, non diet soda) runs in the neighborhood of 900ish calories, so a centaur to just exist would need to eat around 12 Quarter Pounder meals a day just to subsist.

While in the oxygen question there is the benefit of being a poor utilization ratio, the body is actually pretty well versed in conserving calories, and is very efficient (Which is one reason it's so easy to become overweight).

I would presume that a centaur diet would need to be high in fats, as fats carry 9 calories per gram, while meat/carbohydrate each weigh in at 4 calories/gram. For example, an avocado (21 grams fat) has 230 calories, a 146 gram serving of turkey (Same as the avocado serving) has 152 calories, and typical steak at 146 grams (5 oz) is around 400 calories (depending on fat content, lean meat has less calories).

So, a pound of steak comes in at 1200 calories, a pound of avocados comes in at 700ish, so if those were the only two foods available, you would need about 6 lbs each of steak and avocados per day to reach maintenance levels.

The average American I see chowing down manages to get through 900 calories in about 15 minutes at McDonalds, so I would guess that centaurs would need to eat for 1/2 hour to an hour 4-5 times a day to get their needs met, more if they are adapted to make better use of plant material than humans.

Answer 2

Since Centaurs are intelligent and have arms they can raise and collect a much larger array of foods than a horse. I would also expect them in general to have proportionally larger mouths with larger molars for helping ingest the tougher plant tissues.

While a human can survive on bread and water for a very long time, other foods would keep them much healthier. I imagine that Centaurs would eat quite a bit of fruits and vegetables and nuts having a higher calorie content, even though they could 'survive' on grasses and grains.

Omnivorous? Possibly, though I would expect the animal protein to be primarily seafood or birds, more like a vegetarian vs. a Vegan.

Carnivorous? Very unlikely, Carnivores tend to be smaller than herbivores and a Centaur is pretty big and would require a LOT of meat to itself going.

Answer 3

I mentioned birds in my other answer so why not here as well,

Using a gizzard centaurs would be able to digest fibrous foods that humans wouldn't be able to. Then allowing the food to be fermented in a rumen stomach would allow the remaining digestive system to get more out of the plant matter. (breaking down toxins as needed)

Having dexterous hands would allow them to get to food that other animals would have a hard time getting behind spines or in burrs/cupules.

Answer 4

The subject of centaurs eating was (briefly) addressed by C.S. Lewis in The Chronicles of Narnia. In that world, centaurs had two stomachs, one human and one equine, and had to eat to fill both, which meant that they ate a lot, both human and horse food, and spent some time doing so. (ref) Though the mechanics of how they grazed was not mentioned, as far as I remember.

Another point is that, depending on the world, the "human" portion of the centaur may not actually be human-sized, but instead sized proportionately such that the torso of the human half is the same size as the neck/torso joint of the horse, so "small mouth and throat" might not be applicable. - Again, in Narnia, the human portion of the centaur was compared to giants, rather than normal humans. In Nick O'Donohoe's Crossroads series the increased size of the human half of centaurs is also explicitly referenced. (Though their dietary needs aren't mentioned, if I recall.)

Answer 5

I cannot imagine centaurus to be ruminant - chewing the cud all day in the shade? Just the opposite, centaur would be much better hunter than humans are.

Also better farmer: plowing the fields would be easier.

My bet is carnivore like neanderthal man, diet is mostly meat with fruits, cheese and grains added. Just eats three times as much as average human.