Nutrition of the Horse

Ever wondered what was in your horses feed, and how your horse utilises it - or if he needs it?

Carbohydrate
Carbohydrates are the main source of energy and are crucial for correct muscle function and movement, as well as for essential body processes such as breathing, digestion, growth, pregnancy and lactation. Carbohydrates also provide warmth, while any surplus is stored as fat. Starch is a carbohydrate made up of a large number of glucose molecules and makes up 50-70% of cereal grains dry matter. Horses break down starch into glucose in the small intestine where it is then absorbed into the blood. The pancreatic juices contain an enzyme called Amylase which is secreted into the Duodenum which breaks down starch into maltose. Large amounts of starch should not be fed to a horse at one time as the small intestine may not be able to digest all the starch quickly enough.

Protein
Proteins are required for growth, muscular development and for the renewal of body cells as well as for health during pregnancy and lactation. Proteins contain essential amino acids which can only be provided by the food given to the horse. During digestion proteins are absorbed as amino acids and used for growth and tissue repair. In the stomach pepsin begins the breakdown of proteins. The pancreatic juices contain an enzyme called Trypsin which is secreted into the Duodenum which breaks down proteins into peptides then into amino acids. Enzymes are also always proteins and they act as catalysts and speed up chemical reactions within the body.

Lipids
Lipids provide energy and promote the renewal of fat tissue which is required for warmth. They are only needed in small quantities as they are not easily digested and can inhibit the absorption of other nutrients. Horses digest vegetable oil very well and it does not disrupt the microbial environment in the hindgut. Lipase begins the breakdown of lipids in the stomach and the liver secretes bile to the Duodenum, which emulsifies lipids.

Fibre
The end products of fibre fermentation and digestion and can be used as an energy source throughout the day. Fibre is required to keep the digestive process working and moving the food particles through the gut. The digestion of fibre starts in the caecum through the process of fermentation. The caecum begins to digest the roughage through a fermentation process. This process is activated by bacteria and protozoa particular to each type of foodstuff. Cellulose is broken down to release fatty acids - a process which can take several days. The fermentation of cellulose is continued in the large colon.

Calcium (Ca) - is required for the correct formation and maintenance of the bones as well as for nerve conductivity, muscle contraction and in energy metabolism. It is also required for lactation and blood coagulation. Sources include grass, good meadow hay (containing timothy and orchard grass, limestone flour, alfalfa, and clover. A deficiency in calcium can increase the risk of fractures, skeletal defects and increased blood clotting time.

Phosphorous (P) - promotes healthy bone growth and energy production. Good sources of phosphorous are good hay, grass, cereals - especially bran. Deficiencies in phosphorous can lead to skeletal defects and poor growth in youngsters.

Magnesium (Mg) - aids the formation of bones and teeth and is involved in all forms of energy production, nerve and muscle function and normal cell metabolism. It can be found in most feedstuffs, particularly pulses, linseed, turnips, carrots, soya beans, alfalfa as well as good grass and well made hay.


Iron (Fe) - promotes the production of red blood cells and is essential to the formation of haemoglobin which carries oxygen in the blood. It is also necessary for the central nervous system to function. Iron can be found in deep rooted herbs such as comfrey and mineral blocks. A lack of iron may cause anaemia particularly if aggravated by a heavy worm infestation. As the iron contained in the red blood cells is recycled when the red blood cells die, iron is rarely lost from the body unless the horse has worms or sweats a lot from exercise. Additional Vitamin B will aid production of Iron in a horse.

Copper (Cu) - needed in the formation of hair, bone, cartilage and elastin. Copper promotes the utilisation of iron. It can be found in high levels in seed products such as linseed and in feedstuffs grown in soil containing the right levels of copper. Deficiencies show themselves as de-pigmentation of the coat - deficiencies are rare as normal feedstuffs provide adequate quantities.

Selenium (Se) - when used in conjunction with Vitamin E it is considered and anti-oxidant and that it can help prevent cell damage. Selenium can be found in herbage, linseed and supplements. Selenium is toxic if over-dosed. Deficiency signs include weak foals, anaemia, joint abnormalities and in some cases azoturia.

Vitamin A - boosts the horse’s immune system and helps the horse resist disease. It promotes healthy bone and tissue growth and fertility. It improves night vision (didn’t your Mum always say eat your carrots and you’ll see in the dark!) and the metabolism of fats and carbohydrates. Good sources are green leaves, carrots, good quality hay, and cod liver oil. The carotene present in the green leaves is converted into Vitamin A by the horse. Signs of deficiency include suppressed appetite, poor growth, loss of condition, increased susceptibility to respiratory infections, infertility, skin disorders and diarrhoea.

Vitamin D - aids the absorption of calcium and phosphorous in the gut, thus preventing bone defects. It is made under the skin by the horse when in the sunlight and is found in sun cured hay. Cod liver oil may be used in the winter and Greenland where they have no sun for months! Signs of deficiency include swollen joints, skeletal defects and lameness. Overdose is possible and not advised.

Biotin - Biotin is a B vitamin and improves the hoof wall structure, metabolism of fats, proteins and carbohydrates. It is also related to the synthesis of glycerol for body fats, RNA and DNA. Carrots and bananas contain biotin. Since it cannot be stored, it must be present in the daily diet. Likewise, since it is not stored, if an excess of biotin is given in the daily diet, the unused portion is cast off in the urine. Deficiency signs are poor hoof condition and skin changes.

Salt  - Salt should be fed to your horse - especially in spring and autumn when there is excess grass growth and excess potassium. Approximately 2-4 tablespoons per day in the feed. Salt licks are not enough. Without salt in the grass growing seasons your horse could suffer from Grass Tetany.