Why do cattle eat grass and still get fat , providing nutritious milk? If you want to know why grass-eating animals get fat , please read the article below.
When most of us think of protein-rich foods, we probably picture meat, eggs, beans, and the like. However, animals that eat grass, such as cows and horses, have no problem getting enough protein in their diets. Unlike humans, grass-eating animals are able to digest plant cells and absorb the nutrients stored inside, such as protein.
Animals that get all their nutrition from grass and other plants are called herbivores. Herbivores have the ability to do something that humans cannot: digest cellulose. Cellulose is a type of carbohydrate that makes up plant cell walls. These cell walls are tough and difficult to break down, making them difficult to digest, even for herbivores. Herbivores have digestive systems that contain bacteria that have the enzymes needed to break down cellulose. Once the cells are broken down, they can access the proteins, sugars, and fats locked inside the plant cells.

Cattle do not have an upper jaw, so they can only use their tongue to push grass into their mouth, then use their jaws to gnaw off the grass and then swallow it. This grass will be stored in the rumen.
Cattle are ruminants, so their stomachs have a special structure, with 4 compartments. The size of the rumen in adults accounts for more than 80% of the stomach, so its capacity is very large, up to 200 liters. When finished eating, cattle will lie down to rest and push the grass in the rumen up to chew again.
Thanks to the special structure of their stomachs, ruminants can digest cellulose, the main component of plant cell walls, which the human stomach cannot digest. The microorganisms in the rumen of cattle and buffaloes can break down the chemical structure of cellulose to “synthesize” it into many other nutrients.
The beneficial bacteria in the stomachs of cattle and buffalo also help them digest agricultural by-products such as rice husks, hay, cereal hulls, etc.
Grass is mostly water, but inside its dry surface, there are water-soluble carbohydrates, proteins, fibres, oils, minerals and vitamins. So it is a complete diet: everything a cow needs is in the grass. What's more - it is supported by a special combination of four stomachs and powerful gut bacteria.
To enhance the benefits of the diet, many cattle farmers try to plant as much white clover as possible in their pastures (the top layer of soil covered with grass) to provide protein for their cattle. Furthermore, the nitrogen fixed by the clover from the air into the soil helps promote more sugary, energy-dense grasses like rye grass – improving the overall productivity of the pasture and the overall digestibility of the pasture.
The oils in grass contain polyunsaturated fatty acids (PUFAs), which are assimilated into the meat of the cattle and are very healthy to eat. These are Omega-3 and Omega-9 if you don't know.
In short, buffaloes and cows can only eat vegetables and grass and still be fat thanks to their stomach structure and the beneficial bacteria in their digestive tract.