Advanced: Nutrients

Alright so it’s been a while since I’ve done a really good advanced level TheoryThursday so I figured I’d do about a month’s worth in one :) Enjoy!

As always note that this is simply an FYI. Your horse’s diet should be discussed with your vet and equine nutritionist – not concocted off the Internet. This is just so you can sound intelligent when you go to talk to the experts!

There are six types of essential nutrients:

• Water – essential part of every cell


• Protein - building blocks of cells, for growth, repair and maintenance of body


• Vitamins - support vital body functions


• Minerals - build and maintain tissue


• Carbohydrates - used for energy and digestion


• Fatty Acids/Lipids - produce extra energy (backup system for carbs) and used to digest vitamins.

Water

is the most important nutrient in the horse's body. The horse should drink about 12 gallons of water daily -- obviously more in the very hot weather or when in serious work. Water makes up 65% of the horse’s body weight (closer to 80% for foals). Among other things, their bodies use water for:

• Digestion: aids swallowing, provides fluid for food to pass along digestive tract, basis for digestive juices.


• Blood: fluid containing blood cells and nutrients, carries waste from tissues


• Lymph: drains tissue and maintain balance of body fluids


• Urine: excrete waste, regulate levels of sodium, potassium and other electrolytes


• Faeces: supply fluid to aid excretion


• Body – regulate body temperature


• Skin – regulate body temperature (ie remove excess heat as sweat)


• Eyes and nostrils: tears and mucus as a lubricant


• Joints: lubricate


• Milk: 91% of milk of lactating mares.

Proteins

are the building blocks of the cells, and as such are particularly critical for young, growing horses. They create new tissue and repair the old. These are found in oilseed (esp soybean oil – which is about 50% protein), oats, barley, corn and alfalfa. Proteins are made up of amino acids, whose job is to translate plant protein (that the horse has just eaten) into animal protein (that his body can use). There are a whole variety of these amino acids (24 actually :) – of which the two most important are lysine and methionine. They are the most important because the horse needs those two to make use of the other ones.

Vitamins

Vitamins are organic substances needed in small amounts by the body. There are two types of vitamins: water-soluble (which is carried in water, and tends to exit the body fairly rapidly) and fat-soluble (which is carried in fat and can be stored for when the body needs them).

The fat-solubles are Vitamins A, D, E, and K. This is why it is important to have at least a certain percentage of body mass as fat -- if your horse doesn't have enough fat, she can't utilize these correctly.

Vitamin A:
Is made from carotene which is found in green pasture grasses and good quality hay. Is responsible for night vision, important for reproduction and embryo creation, helps improve the immune system, and keeps eyes/skin/hair/nerves/hooves/etc healthy. Vitamin A deficiency can cause night blindness; toxicity can cause fragile bones or overgrowth of bones and/or pregnancy issues (ie malformed foetus).

Vitamin D:
Found in sunlight or a little bit in sun-cured hay. Helps regulate calcium levels (hence why most calcium supplements include Vitamin D :). Vitamin D deficiency is rarely a concern due to the fact that horses need very little of it but in extreme circumstances can cause rickets (as w/ people, causes bone deformities). Vitamin D toxicity is incredibly rare since the body only makes as much D as it needs; were it to happen it would result in calcification of soft tissues.

Vitamin E:
Found in forage – note that Vitamin E is lost when feed is heated during processing or over time. Older plants have less E than younger ones. It is necessary for fertility, production of red blood cells and ability to carry oxygen in teh blood. Deficiency will result in muscle issues (esp when combined w/ selenium deficiency -- hence why vit E and Selenium supplements are often sold combined). These issues would display as constant shifting of weight or lying down, no ability to keep muscle tone, trembling, etc. Vitamin E toxicity is essentially a non-issue. In people it can cause impared bone calcification, but doesn't seem to happen in horses. Note though that too much selenium (see minerals) which is often combined with the E supplement IS a concern.

Vitamin K:
Found in forage, vitamin K helps with blood clotting. Deficiency is very rare, usually only caused if mouldy hay is fed (as it actively works against vitamin K) and would result in blood not clotting properly. Toxicity is also very rare (the "safe" rate is something like 1000 times the daily recommended intake) although has occasionally be caused by injection resulting in renal/kidney failure.


Ok so those are the ones that can be stored in your horse’s body. The water soluble vitamins include all the B vitamins (cause it’s easier to remember a bunch of Bs then to give them each their own letter!) as well as C. These are usually flushed out of the system through the horse’s urine and so are rarely toxic, but by the same token, deficiencies are noted much more quickly.

Vitamin B6:
Is required to allow the amino acid tryptophan to be used. This is found in most feeds and has no known deficiency or toxicity issues.

Vitamin B12:
Is created in the horse’s digestive tract (and requires the mineral Cobalt for this to happen!) B12 is used in the metabolism of faty acids, carbohydrates, and proteins. Also helps prevent anemia. It has no known deficiency or toxicity issues.

Vitamin B3 - aka Niacin
Found in forage and produced by the horse's digestive system, Niacin is required for metabolism. It has no known deficiency or toxicity issues.

Vitamin B1 - aka Thiamine
Found in cereal grains, Thiamine aids in carbohydrate digestion and is required for appetite. Toxicity is a non issue but deficiency can cause:
- nervous system issues (incl pain, swelling and lethargy)
- loss of appetite
- muscle twitching
- slow heartbeat
- lack of coordination
Note that deficiency is usually not an issue due to it being so available in the horse's diet. However, should the horse eat a large amount of Bracken Fern, it will block the B1 resulting in the deficiency.

Vitamin B2 - aka Riboflavin
Found in leguemes and grass hays; a moderate amount can also be produced in the digestive system. Riboflavin helps make coenzymes which are essential for energy release and the proper functioning of the nervous system. Toxicity is very rare and would cause weight loss. Deficiency is a non-issue.

Vitamin C
Is generally synthesized from glucose in the horse’s intestines. This is an anti-oxidant with no known deficiency or toxicity issues. (Although in people vitamin c deficiency produces scurvy)


Alright – you got all that? You’re half way through now! Hahaha I did warn you it was an intense one :) So we’ve done water, proteins and vitamins. And the vitamins are divided into fat soluble (A, D, E, K) and water soluble (various Bs and C).

And now we’re on to...

Minerals

Minerals are inorganic substances (as opposed to the organic vitamins we just discussed) that are required in tiny amounts but are absolutely critical for a healthy horse – 90% of the skeleton is made up of minerals. Note that overfeeding minerals is likely to cause more harm than overfeeding vitamins.
There are two types of minerals, macrominerals (aka major minerals) and microminerals (aka trace minerals).

Macrominerals

• Potassium maintains PH and fluid levels in the cells. This is used every time your horse uses a muscle. Found in forage. May need to be supplemented (ie electrolytes) in a horse who is exercising heavily for a long period of time without eating (esp endurance horses) in hot humid weather


• Chlorine (salt ) is important for cell function. Found in salt.


• Sodium (salt) similar to potassium but arguably even more important. Hard to find in normal diet but a primary component of salt which is why it is recommended to have free choice salt always available (particularly loose salt as some have trouble with the blocks). If your horse is randomly licking odd things (esp your sweaty hands!) the odds are good he needs more loose salt.


• Calcium is important for bone development and maintenance. 90% of calcium in the body is found in the bones. Comes from legumes. Amount must be carefully balanced with phosphorus.


• Phosphorus is also important in bone formation and maintenance as well as creating cell energy (ADP/ATP). 80% of phosphorus in the body is found in the bones. Comes from plants. Amount must be carefully balanced with calcium.


• Magnesium is important in skeletal development, muscles, and nervous tissue. Lots of "de-stress" horse products use magnesium to help chill out the horse as magnesium deficiency can lead to being very tense and high strung. Found in most feeds, but often not sufficient to meet horse's daily needs.


• Sulfur is involved in just about every substance in your horse's body. Critical component of key amino acids (which make up protein structure) and important to both insulin (sugar regulator) and biotin (hoof growth) as well as many others. Found in forage.

Microminerals
No less important than macrominerals, but required in tiny amounts.

• Iron is important for blood transportation around the body; iron deficiency can result in a weak or anemic horse.


• Zinc is important in bone development, blood clotting, coat quality and reproduction.


• Manganese is important in cartilage and bone development and mineral utilization.


• Copper is important in bone and cartilage development and iron utilization. Molasses is particularly high in bopper.


• Iodine regulates thyroid activity and aids metabolism. Also particularly important for pregnant mares. . Iodine is usually supplemented by feeding iodized salt.


• Cobalt is important for blood cell formation and the synthesis of vitamin B12 (see above :)


• Selenium is important to reproduction, growth, and the immune system. Note that too much selenium can cause all sorts of problems from abdominal pain and lethargy to hair loss, blindness and laminitis.

Note that there are two ratios you must be aware of for minerals:

• Calcium: Phosphorus -- roughly 2:1. Should it drop too low, the horse won't be able to absorb the calcium, resulting in deficiency and weaker bones. Note that hay and grasses are high in calcium, low in phosphorus while grain is high in potassium and low in calcium.


• Zinc: Copper -- this one isn't set because it'll change dramatically from horse to horse, but it seems the higher the ratio, the more likely problems will occur.

Carbohydrates

Carbohydrates are plant starches that your horse uses for energy. They are found in hays, grains and grasses and are the most usual source of energy. Note that excess energy will be stored as fat so be careful to feed the right amount for the amount of work he’s doing!

Fatty Acids/Lipids

Fatty acids are used to carry certain vitamins through the bloodstream and are essential for metabolism. They also affect skin and hair condition and the rate of growth of young horses. Fats provide roughly 2.5x the amount of energy as carbs and are an “emergency backup system” for use when your horse’s body is stressed (be it from too much work, illness, or missing his weekly trip to the psychiatrist!) The best source for these are wheat-germ oil (or if you’re on a budget, corn oil :) Note that high-fat feeds tend to spoil quickly so be careful if you choose to feed them.

And now you know far more than you ever wanted to about nutrients :) Congratulations.