In part two we explored the ethical issue in vegan diets. In part three, I am going to talk about how the digestive systems of ruminant and carnivore animals are different.
What do I mean when I say plants bite back? In part one, I told you that ruminant animals have a chambered stomach. However, a carnivore, such as your dog, has a simple stomach that needs hydrochloric acid to digest their food. So what is the difference? A ruminant animal with a chambered stomach, is designed to only eat plants. They have a chambered stomach so they can ferment their food. Why is that important you may ask. Because plants bite back.
When a carnivore such as a wolf or lion hunts for their food, the food has a defense mechanism. They can run away. Plants also have a defense mechanism. It is called “plant toxins”. Why do plants and prey animals have these defenses? Because plants, as well as prey animals, don’t want to be eaten.
Why is it that ruminant animals can only eat plants. Because cows have a fermentation tank in their chambered stomach.
“It is a very popular but incorrect thought that a cow has 4 stomachs.
To be precise a cow does not actually have four stomachs but in fact has one stomach
but that has four stomach chambers. Each chamber has a different but an important part
to play in digesting food. The grass a cow eats has a long and complicated process from
the eating stage to finally being passed back out the other end!
The four chambers of the cows stomach are the rumen, the reticulum, the omasum and the
abomasum. The grass or digested material passes through each of these four chambers in
turn and is slowly digested and the goodness drawn out. ” 
Dogs, on the other hand, have a monogastric digestive system- very different from a cow. A short digestive tract where
meat is easy to digest with an overall simple design. I wrote about the digestive system of the dog in more detail here.
“Although many dogs may like to eat vegetables, most of the nutrients are completely unavailable to dogs. Vegetation will pass quickly through a cat or dog without having the needed time for complete digestion and provide little nutrition to the animal.” 
I see this in my own dogs if they get ahold of an apple off the tree in the yard. Or when I used to feed carrots. These things come out the same way they go in.
Let’s take a look at the digestive system of the bovine, or any ruminant animal such as a goat, sheep, bison, elk or deer.
Earlier I mentioned the defensive mechanism of plants called plant toxins. Toxins are things like oxalates and lectins. (don’t even get me started on nightshades) Oxalates are a compound found in some foods, which when consumed exits the body through the urine. Excess consumption has been linked to gout and kidney stones. Then there is lectin. Foods such as beans and grains, need to be cooked or fermented to reduce lectin content. Did you know that ricin from the castor plant is a powerful lectin toxin that is so deadly there is no known antidote. These are why plants bite back. These are the substances that need to be neutralized in order for nutrients to be absorbed.
How is this accomplished? Fermentation. Humans have fermented foods for many centuries. Plant and animal foods alike. Think Sauerkraut, kimchi, sourdough bread, yogurt, kefir, beer and salami. However, dogs can’t ferment their food, so it needs to be run through a ruminant animal first. How is that done you may ask? How does the cow ferment her food. In her chambered stomach, which is full of microbes. Another thing fermentation does is break down cellulose, the wall of the plants’ cell. A dog can’t do that. It takes more time in the digestive tract and fermentation.
Let’s take a look at that stomach.
“1. The Rumen – This is the largest chamber and can hold up to 150-200 litres of partly
digested food. The Rumen is full of good bacteria and this softens and helps digest the food.
The bacteria ferments the carbohydrates in the food to allow the cow to produce energy.
In doing so gas is produced (approx 500-1500 litres a day), approx 30% of this is methane
gas and is expelled during belching. This is also how the foodstuff is passed from one
chamber to the next.
2. The Reticululum – This softens the food even further and forms it into small lumps of cud.
The cud is returned to the cows mouth and chewed approx 40-60 times before being swallowed
again. The reticulum also prevents large items from passing through the stomach this includes
items which the cow has eaten which are not food, e.g plastic, packaging etc.
Its like a safety mechanism for the cow. The material sits here and will not pass through
to the next chamber, eventually the items will build up and the cow will vomit it back up.
3. The Omasum – This processes the cud further by pressing and breaking it up.
It is then filtered. The omasum also regulates fluid absorption in the gut.
4. The Abomasum – This works similar to the human stomach. The food is finally digested
by the stomach juices and the useful nutrients are absorbed by the blood.
The waste is then pushed out into the intestines and finally out.” 
During all of this process, tiny microbes are also at work fermenting, processing and breaking down the plants to make the nutrients bioavailable. And to take the bite out of the plants. A dogs body simply can’t do that.
You might ask, can I feed my dog fermented veggies like sauerkraut? You could, but unless you know for sure that your dog does not have a problem with histamines, I would not recommend it.
To parody Kelly Hogan: “Feed the meat, save the canines”
In part four, we are going to look at two brands of vegan kibble dog food. V-Dog and Petaluma.
How’s the ride so far?
  act for libraries.com
 Jennifer Lee ‘The Inner Carnivore”