How can horses and cattle build so much muscle when all they eat it grass/wheat?
In: Biology
The cattle I know make daily trips up and down big hills in their pastures. Grains like wheat and corn do have fats, but most of their grazing on the hill is grass and that’s not fattening at all
They have different digestive systems. They both use bacteria to ferment cellulose. To humans, cellulose is “fiber”, it is indigestible, although it helps us poop. Grass is like bread or rice to cattle, they digest it and gain calories from the fiber. [Grass is up to ten percent protein](https://standleeforage.com/nutrition/nutritional-papers/big-two-forage-grasses-timothy-and-orchard), and they eat a huge amount of it.
You’ll notice that cattle and horses have very large bellies. This is to house large stomach and guts that act as fermentation factories.
Microbes live in their guts and break down the plant matter into more nutritious compounds. This is like an internal “cooking” step. These compounds help build the body and muscles of the animal.
Carnivores don’t need such huge bellies because they directly eat nutritious meat of other animals. Humans have also skipped having a large belly because we figured out how to cook food. Cooking breaks down food so we don’t need a huge gut to help us digest.
Horses and cows have very different digestion systems then humans and are much better suited to digesting plant fibers that we can not digest. In addition they are able to synthesize a lot of vitamins and amino acids that we are not able to synthesize so they can keep to a less diverse diet. They are also better at converting sugars from the fibers to fat and protein. And by eating all day long they are able to get a lot of energy that gets converted to protein to build muscles. This being said their digestion system is a lot less efficient then ours requiring them to eat all day long to get enough energy. And most of the muscle mass is used to be able to carry around that huge stomach and liver that is required to live on a diet consisting of mainly grass.
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