Necessary Components for Equine Feeding
The suitability or otherwise of an equine diet should be determined not so much by the types of feeds it includes, but rather what those feeds contribute in the way of nutrients. The nutrients, which are essential to life are:
· Carbohydrate
· Protein
· Fat / Oils
· Minerals
· Vitamins
· Water
Carbohydrate
Carbohydrates fall into two categories, structural carbohydrates and non-structural carbohydrates.
Structural Carbohydrates, also known as Insoluble Carbohydrates are contained in forage. These are broken down in the hind gut of the horse by the gut microflora. The end result is Volatile Fatty Acids (VFA's) that are absorbed and used as "non-heating" sources of energy by the horse. In most horses, volatile fatty acids are the main energy source.
Non-structural Carbohydrates - starches and sugars; also known as Soluble Carbohydrates, such as those contained in cereals. These are broken down in the small intestine and absorbed to provide energy that is more rapidly available - "heating" type of energy which can make some horses excitable.
Protein
This is an important component of all animal tissues. Without the synthesis of protein, life would not exist. All proteins are chains of repeating units call amino acids, and it is these proteins that are broken down by enzymes in the small intestine. Proteins in excess are wasteful and the horse has to break it down. Part is excreted in the urine or may be used as an expensive and inefficient energy source. Horses that are working harder need carbohydrates and/or fat.
Fats/Oils
Fats and oils are potent sources of energy for the horse. A concentrated source which typically contains twice as much energy as cereals and more than three times that of forages.
Fat and oils are a mixture of compounds known as fatty acids. The horse did not evolve naturally to digest fat and oils but it nevertheless is very efficient in digesting them in the small intestine.
The use of fat and oils in the diet provides more endurance to the horse and the use of high oil diets in hard working horses can lead to reduced fatigue and improved recovery.
Vitamins
These are a group of chemical compounds which are vital for life. They are required in tiny quantities for the normal functioning of the horse. Some chemical compounds take on the function of vitamins after undergoing a chemical change. These compounds are known as Pro Vitamins e.g. B-caratene changes into Vitamin A. There are 15 vitamins which are known to be essential to the horse. They are split into two groups: Fat Soluble and Water Soluble.
Fat Soluble vitamins can be stored in the fat deposits of the horse and in the liver. Most of the fat soluble vitamins are abundant in fresh herbage which means that the horse can store them through the summer months for use later in the winter. They can therefore become toxic if overdosed with supplements as well. Vitamin A, D, E & K are fat soluble vitamins.
Water Soluble vitamins are soluble in water. When excess are fed, they are broken down and excreted through the urine. The horse can make some of its own water soluble vitamins in the hind gut (via the microflora). Vitamin C and B Group (Thiamine, Riboflavin, Pyridoxine, Cyanocobalamin, Folic Acid, Pantothenic Acid, Choline, Biotin, Inositol, Niacin) are water soluble vitamins.
Supplementation of vitamins may be required due to:
· Poor quality feeds being fed
· Hard work being undertaken by the horse
· Stress situations
· Illness
· Young or old horses
Minerals
These are split into two groups:
· Those needed in larger quantities (macro minerals)
· Those needed in minute quantities (trace minerals)
Macro Minerals include: calcium, phosphorus, magnesium, potassium, sodium and chloride.
Trace Minerals include: iodine, cobalt, copper, zinc, iron, selenium, manganese, florine and chromine.
Approximately 21 minerals are required in the diet and these are essential for health and development.
The horse's mineral intake will depend greatly upon the water and soil content of the area. If fed compound feeds then minerals are added. Some minerals interfere with the absorption of others in the gut so overfeeding of one may lead to a deficiency of another. If phosphorus levels, for instance, are too high then less calcium will be absorbed and deficiency may result.
Water
About 70% of the bodyweight of the horse is made up of water. This increases to 75-80% for a foal! Water is required for many different life functions including:
· Temperature regulations (sweating)
· Excretion (urine)
· Mare's milk
· A medium in which chemical reactions take place
· A solvent in which substances can be dissolved and transported
· Helps to give cells their shape
Horses should have a fresh supply of clean water at all times. The amount drunk will to some extent depend upon the amount of dry feed the horse is eating. The horse at grass takes in much more water as grass contains 75-80% moisture. Horses should not be allowed to drink large quantities when they are hot from work as their respiratory rate is high. Let the horse cool down for 15-20 minutes before giving access to water or allow only a small drink at first and give another 10 minutes later.

Do not give a hot horse very cold water.