Welcome back! In the last article I reviewed 3 types of sugar important to horses. They were glucose, which is a single molecule of sugar (monosaccharide), starch, which is a chain of glucose molecules linked together (polysaccharide) in a way the horse can digest using enzymes, and finally cellulose which is the same chain of glucose molecules linked together in a different way so that the horse cannot digest it but the gut microbes can.
Remember also that every glucose molecule is made up of the elements C H and O (carbon, hydrogen and oxygen). Do you know what elements make up fat?
C H and O. Yes the same atoms are used to make fat but they are put together differently. Is it possible that a molecule of glucose could become a molecule of fat? Definitely. In fact every time there is an excess molecule of glucose, the body converts it into a triglyceride (a type of fat) and stores it as fat on the body.
How about proteins? They are made of amino acids chained together like letters make words. What elements are in amino acids? If you say C H and O you would be almost correct. Added to these is nitrogen (N) and you have an amino acid. Of the 20 amino acids there are 2 that also have a sulfur element. Can an amino acid become a sugar? Absolutely through a process called gluconeogenesis.
Basically you, me and our horses are mostly made of the solid carbon and 2 gasses - hydrogen and oxygen. Have you ever burned white table sugar? If you have then the gasses are evaporated leaving you with a solid black substance which is the carbon - and a ruined pan. The concept here is that the body is a simple chemistry set with only a few ingredients and how those ingredients are put together will make the variety of things needed to make you and your horses operate. So everything in us has the ability to become something else - like a horse trainer could become a stall mucker if needed.
I really want to make feeding a horse something we all can understand because once understood, you will never feed your horse incorrectly ever again. To do so, this concept needs to be fully understood. Everything in the body is a variation of the basic group of C H and O. These molecules are so small that no one has ever photographed them. Think of it this way. A cell is very small but we can see them under a microscope. Within a cell are between 1 and 3 billion proteins and each protein is made up of hundreds, thousands and even tens of thousands of amino acids. And every amino acid is made up of C H O and N elements. The body has the ability to break apart the molecules and reform them into something completely different according to it’s needs.
We need an example from the real life of a horse. I’ll use Buster the pony. He is out grazing on grass all summer which is softened by chewing, gastric acid, enzymes and gut bacteria. The first to come out is the starch which is how the plant stores energy. Also coming out are the plant proteins which are broken into smaller peptides (like syllables of words) and the individual amino acids. But the cellulose in not digested until it reaches the cecum and colon and the bacteria there break apart the bonds between the glucose molecules. Then the bacteria turn these glucose molecules into short chain fatty acids. These are what the horse absorbs and uses for energy. In essence he is eating a high fat diet. This is very important to understand especially when I discuss the 2 basic fuels of the body - glucose and ketones.
A meal of grass provides horses with a lot of fat, some sugar and a little bit of amino acids. All of these are small enough to cross the intact gut membrane and are sent throughout the body for use. Glucose can power some of the functions but where it first goes is to the liver, muscles and brain where it is stored as glycogen. This is where they get quick energy for bursts of speed. It is similar to starch of plants but it’s got a different name in animals (glycogen). Any excess is transported by the hormone insulin to fat cells where it triggers the cell to make more fat.
Glucose in the form of plant starch becomes more abundant in summer and autumn before winter when food becomes scarce. The purpose of finding sugar laden foods is to create the fuel storage of fat so we have something to use when there is no food. Horses eat as much grass as possible during the summer and fall and are supposed to gain fat weight doing this. Most importantly, as long as there is glucose available, insulin being used to get glucose into cells and to store excess glucose as fat also prevents the conversion of stored fat into the alternative fuel called ketones. When food becomes vary scarce and body fat is gone, the proteins of the muscles are converted into glucose to prevent the horse from dying.
The fattening and thinning of horses and humans is millions of years old and it works. However when there is a constant supply of glucose throughout the year, fat continues to be formed causing obesity. And glucose is available to humans and horses every day throughout the year in the form of fruits and grains. The excess glucose overworks insulin and the power generators within the cell called mitochondria. At some point the job of insulin and the ability of fuel conversion into energy is compromised and is referred to as insulin resistance.
But it is actually much worse. Remember the good gut bacteria happily digesting cellulose? They are replaced with bacteria happy to live in a high carbohydrate diet. Now the fiber cellulose is not effectively digested and the health of the gut becomes compromised. Some of the effects of this include wet feces or squirts, poor absorption of protein and a horse that becomes hungry all the time.
Why is the horse hungry? Because in the abundance of glucose, energy needs are not met. The system is overworked because it was never designed to work this way every day. They need time off from the fuel glucose. Horses need fat to become satiated and function efficiently during the lean months and without the good gut bacteria, the fat isn’t made. This leads to the next article.
The take home messages:
1) Carbohydrates, fats and proteins are built on the foundation of a simple molecule made of carbon, hydrogen and oxygen atoms. How this molecule is put together into chains or whether a nitrogen or sulfur atom is added will determine what it is and what it does. Enormous combinations of these molecules provides the variety of materials needed to make the body take form, function and survive. These molecules can transform between these three forms (sugar, fat, protein) to meet the needs of the horse. The most important point is that the horse has evolved to take in a limited form of food to make all of this work properly. Adding foods that have not come with this evolution alters the process leading to imbalances and disease. Anything added to this diet in the past 4000 years when they were domesticated by humans is considered new to a horse and his gut microbes that are 55,000,000 years old (55 million).
2) Continuous feeding of glucose laden foods in the form of plant starch (grains), sugar cubes, carrots and apples overworks the insulin system, the mitochondria energy generator, cause increased storage of fat and prevent the loss of this fat. This imbalance to the time tested system of the horse leads to disease in all systems of the horse including protein deficiency, muscle loss, lameness, hormonal disruptions, neurological syndromes and autoimmune diseases.
Don’t worry if you feel a little overwhelmed especially when some of this is so different from what you thought you knew. Just keep asking this: Is what you are doing now working? If not, stayed tuned. More next week on gut microbes and the mighty mitochondria.
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