In this post I will give an overview of the composition of the feedstuff. As you can see in the following diagram, there are two main components in food: water and dry matter. The nutrients are found in the dry matter fraction. This is where we find the minerals, the vitamins, the carbohydrates, the fats and the proteins. (click on diagram to enlarge)
Water
Water is an essential component of the horse's diet. Water is required for transporting nutrients in the body. It's involved in the thermal regulation. It's essential for the excretion of the waste products but also for the gut function.
Carbohydrate (CHO)
The carbohydrate falls into two categories:
- Structural CHO
It's the fibrous fraction of the food. The digestion of structural CHO takes place in the large intestine by microbial fermentation. It produces volatile fatty acids. It's the main energy source for most horses. It's a slow release energy but more steady and constant.
- Non-structural CHO
Non-strucutral CHO are in the cell content and they constitute the storage carbohydrate of the plant (energy source for the plant). We find here the starch, fructan and simple sugar. The digestion of starch and simple sugar takes place in small intestine by enzyme. It's a rapid source of energy.The fructans cannot be digested in small intestine and so travel through the large intestine where they are fermented by the microbial population.
!!! If non-structural CHO are present in too big quantity the small intestine cannot digest them and the remaining undigested starch and sugar will end up in large intestine. The product of microbial fermentation will be lactic acid that can alter the gut environment. That is why we want to feed small amount of starch and sugar.
Oil and Fat
The fats that are present in forage are simple in structure. Fats added to the diet are mostly triacyglycerols. Horses don't require high level of fat. Fat is added to the diet to increase the energy content as it is a concentrated source of energy (2x energy content of cereals). The digestion takes place in the small intestine.
We are seeing an increase interest in the two essential fatty acids, Omega 3 and Omega 6, in terms of potential health benefits but more studies need to be done.
Protein
Proteins are required for structural purpose (muscle, skin, hair), formation of enzyme, hormones and immune system.
There are two categories of protein: essential and non-essential amino acids. Essential has to be supplied in diet and non-essential are synthesized by the animal.
Lysine is an essential amino acid.
Protein requirement will increase with work, growth, pregnancy, recovery from injury, muscle loss, surgery, etc.
!!!! Too much protein will damage liver and kidney and create mineral imbalance!
Minerals
Minerals are required for growth, transport of energy, co-factors of enzyme, etc. They are mainly absorbed in small intestine. There are two categories: macro minerals and trace minerals.
Macro minerals are required in large quantities (Calcium, Phosphorus, Chloride, Sodium, Potassium, Magnesium, Sulphur). Trace minerals or micro minerals are needed in very small quantities (Cobalt, Copper, Molybdenum, Zunc, Manganese, Iron, Floride, Iodine, Selenium, Chromium).
!!!! Ratio between some minerals is very important like Ca:P 2:1 Calcium has to be twice as Phosphorus. Calcium has a good ration in forage but poor in cereals grains.
Another important ration is the Cu:Zn 3-4:1
Vitamins
Vitamins are required in small amounts but they are vital for many bodily functions like vision, immunity, growth, bone development, etc.
There are two categories of vitamins: fat soluble (A, E, D, K) and water soluble (C and B Complex).
The water soluble are not stored but are produced or synthesized by the organs.
