Understanding Cow's Digestion

Cow in grass

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Many people don't understand cow's digestion. Cows don’t get their energy from grass or grains.  Surprised?  When cows eat grass, silage or grains it all goes into their multiple stomach system where the incoming feed is converted, by fermentation, into fats.  Yes, surprise surprise, these fats are what provide the cow with energy.

The fats generated in the cow’s digestive system are known as volatile fatty acids (VFA’s) and consist of acetate, propionate and butyrate which are then passed into the cows true stomach (abomasum) then into the small intestine to be absorbed into the cow’s blood stream and used as the cows main energy source.

So, you could say that a cow is fat adapted.  To be this way their multiple stomach system works on the incoming feed using microbes that ferment the feed and convert it into a variety of fats (fatty acids).  When people eat plants, they get their energy not from fats but from dietary glucose which is completely different for a cow which only gets a tiny amount of energy from glucose.

A large number of ruminant animals eat this way including: cows, camels, sheep, goats, buffalo, deer, yaks, elk, giraffes, antelope, okapi, bison, moose, gazelle, ibex, kudu, and musk oxen.  Their digestive process is uniquely specialized to make these fats from plants and is totally different to a human digestive process.

For these ruminant animals to get glucose, the plants are first chewed up, mixed with saliva, then converted to fats (fatty acids) by microbes in the rumen. Should a cow need glucose, some of these fats are converted by the liver into glucose using a process known as gluconeogenesis.   Humans also can also generate glucose, as we also have the capability to convert protein or fat into glucose by the same process.  This is a demand-driven process which only activates as glucose levels drop and therefore the concern that some people have, that eating too much protein will generate too much glucose is unfounded.  A study that set out to establish what proportion of protein was converted to glucose, even under fasted conditions, found that only about 8 percent of the dietary protein was converted to glucose. (Diabetes 62:1435–1442, 2013).

Another group of animals known as “hind gut fermenters”,  ferment the plant matter in the colon and cecum after it leaves the stomach.  This also produces VFA’s (fats) that provides the animal with most of their energy from fiber that has been converted into fats.  This group including horses, donkeys, rhinos, gorillas, rabbits, zebra and elephants do get some nutrition directly from glucose.

When humans eat plants, our gut is not designed for bulk fermentation, we primarily use the glucose extracted from carbohydrate directly.    This means that normal food to these animals is not ideal food for a human. 

Seek professional medical advice before dietary changes, particularly if on medication.  George Elder, Health Coach, Diploma in Nutrition. 

“The best thing you can do for your health is eat better”.