Grazing Not Browsing -Decomplexicating Equine Nutrition Part 1 of 12

Browsers are people who stand in front of the refrigerator with the door wide open looking for something - anything - to eat. Right?

Actually there is a difference between a grazer and a browser technically. Horses are grazers and ruminants (cattle, deer, sheep, goats, and many more) are browsers. Lets look at each.

A very long time ago every specie developed a way to feed themselves. The idea was to take things that surrounded them and eat them to create the needed energy to survive and reproduce. It is a simple concept and one I really can’t understand. Why can’t we just face the sun and drink some water? No, we must kill things and eat them. Thankfully most humans don’t worry about being eaten and in this country horses are somewhat safe. The cow, pig, sheep? Not so lucky. Same with the plants we eat which are also killed for consumption. So are the plant’s babies (seeds) but more on this later.

We all have a tube running through us that starts at the mouth and ends at our anus. You and me, the horse, the dog, - you get the idea. Every one of these tubes have developed in a distinct way to digest the foods around us. The ruminants have won the “best in class award” because they can eat woody things called lignin. This includes twigs, bark, saplings and other stiff plants. They can also make almost all of the proteins needed to survive and grow. This is why you can see ruminants living in the poorest conditions and survive and often thrive.

Horses on the other hand cannot digest lignin. What they are very good at is digesting cellulose which is like lignin but not as robust. Cellulose is found in the cell walls of all plants grown on land. It is made up of a sugar called glucose. Making up the sugar storage of the plant is starch. Without having to know organic chemistry, I want to tell you exactly what starch and cellulose are.

We need to start with one molecule of glucose, the most common sugar. Each molecule is made up of 3 different atoms: carbon, hydrogen and oxygen. We will call these C H and O in the future. Through the magic of chemical energy, C H and O connect together in a simple pattern of a 6 sided ring or hexagon based on 5 C atoms and 1 O atom. For a visual, think of a stop sign in the shape of an 8 sided ring or octagon and pretend it has 6 sides. Around this ring are 12 H and 5 O atoms, but don’t worry about this now. Just pretend you are looking at a 6 sided stop sign and think of this as one molecule of glucose. There are other variations and combinations of this structure that make up the other sugars such as lactose and fructose but we want to talk about starch and cellulose.

https://socratic.org/questions/what-is-the-chemical-structure-of-glucose

Take one “stop sign” or glucose molecule and attach it to another molecule of glucose using a bonding glue. Now your visualization looks like “stop-stop.” Keep going and add a thousand glucose molecules together. stop-stop-stop-stop-stop-stop-stop-stop-stop-stop-stop-stop-stop-stop- and so on for thousands of units. This is what starch is and you and your horse can digest starch using our enzymes breaking it down into the simple sugar glucose.

Starch - the glucose molecules are strung together in the same position.

Now bond your glucose molecules so that every other glucose molecule is upside down. In the 6 sided stop sign it would look like this: stop-sʇod-stop-sʇod-stop-sʇod-stop-sʇod-stop-sʇod-stop-sʇod-stop-sʇod-stop-sʇod-stop-sʇod- and so on. This is cellulose and another word for this is fiber.

Cellulose - the glucose molecules are connected with every other molecule upside down.

What is necessary to understand is that you and your horse can NOT break the bonds of cellulose using the enzymes we have. In fact no animal can digest cellulose. What we all have are bacteria in the colon (large bowel) that CAN break up cellulose into the individual glucose molecules. But because it is an inefficient way to get energy, the horse developed a very large hind gut and a set of teeth to continually harvest enough grass and other forms of cellulose to get the energy it needs to survive the day.

Ruminants on the other hand can eat both cellulose and lignin. Lignin is like cellulose with the addition of an alcohol unit which the rumen bacteria break down. The ruminant then pushed this mix back up into his mouth and re-chews the material (chews the cud) and swallows it again this time bypassing the rumen and heading back for the regular digestion that is similar to the horse.

The take home message is that horses developed specific anatomy for digesting cellulose and because of this, it is the primary way a horse should eat. Grass therefore is the ideal food along with other non-woody plants and leaves. This does NOT include seeds such as wheat, oats, barley, chia, sunflower, corn and any other seed you can think of. These seeds contain starch which is a simple sugar and not cellulose. The bacteria in the gut of the horse become unhappy when simple glucose is presented to them not in cellulose form. Other bacteria start to take over and can be considered “bad” bacteria because they are very efficient in taking the starch and converting it to sugar giving the horse a high sugar diet.

But wait! Don’t the “good” bacteria break down cellulose into glucose molecules too? Isn’t this also feeding the horse sugar? The answer is a solid NO!

I leave you hanging on that because it leads into the next article. But simply put, starch is broken down into simple sugars killing the good bacteria and causing lots of problems in the horse including insulin resistance. Cellulose is NOT broken down into a simple sugar but into something you will not believe (hint: it makes energy). Stay tuned!