Feeding horses: Back to the basics, Part 2 (Animal Science Update)
Many people who care for horses might be fully capable of feeding horses and keeping them healthy, but do they really know the basics behind why we feed them the way we do and what they really require?
This article is the second in this basic nutrition series and we will be focusing on the six classes of nutrients that horses need to survive. Horses require the same nutrients that all living things require, these include water, fats, carbohydrates, protein, vitamins, and minerals.
First let’s take water.
Water is the most important nutrient; Horses can’t live long without it! Always make sure there is an adequate, clean supply of water.
Horses generally drink about 2 quarts of water for every pound of hay they consume.
In high temperature, hard work, or for the lactating mare the water requirement may be three to four times the normal consumption.
Signs that your horse may be water deficient include decreased feed intake and physical activity, and signs of dehydration like dry mucous membranes in the mouth, dry feces, and decreased capillary refill time.
Possible causes of water deficiencies include no water source, low water palatability, or accessibility (frozen or receiving or contaminated), or illness.
Fat can be added to a feed to increase the energy density of the diet. Fat has 9 Mcal/kg of energy, which is three-times that of any grain or carbohydrate source.
However, what is unique about fat is that the energy is released slowly, so will not create an excitable horse like carbohydrates can.
Fat is normally found at 2-6 percent in most premixed feeds; however, some higher fat feeds will contain 10-12-percent fat.
In another article we will talk about fat supplements, but some of these will include ingredients like vegetable oils, rice bran, flaxseed, fish oil, etc.
Carbohydrates are the main energy source used in most feeds meaning most grains have most of their make-up as carbohydrates.
The main building block of carbohydrates is glucose. Soluble carbohydrates such as starches and sugars are quickly broken down to glucose in the small intestine and absorbed.
Insoluble carbohydrates such as fiber (cellulose) bypass enzymatic digestion and must be fermented by microbes in the large intestine, which takes a lot longer to release their energy sources, namely volatile fatty acids.
Soluble carbohydrates are found in nearly every feed source; corn has the highest amount, then barley and oats.
Forages normally have only 6-8-percent starch but under certain conditions can have up to 30 percent in all the soluble carbohydrates (sugars included). Sudden ingestion of large amounts of starch or high sugar feeds can cause colic or laminitis.
Energy isn’t one of the six nutrients because the horse cannot physically consume energy, however it is a requirement for sustaining life.
Horses exercising, growing, pregnant in late gestation or early lactation need increased energy in their diet.
Signs of energy deficiency include weight loss, decreased physical activity, milk production, and growth rate.
However, feeding a diet too high in energy can cause obesity increasing the risk of colic, laminitis, and contribute to increased sweat loss and exercise intolerance.
The most expensive portion of a horse’s diet will be the Protein.
Protein is used in muscle development during growth or exercise.
The main building blocks of protein are amino acids. Soybean meal and alfalfa are good sources of protein that can be easily added to the diet.
Second and third cutting alfalfa can be 25-to 30-percent protein with a good balance of the necessary amino acids and can greatly impact the total dietary protein.
Most adult horses only require 8-to 10-percent protein in the ration; however, higher protein is important for lactating mares and young growing foals.
Signs of protein deficiency include a rough or coarse hair coat, weight loss, and reduced growth, milk production, and performance.
Excess protein can result in increased water intake and urination, and increased sweat losses during exercise, which in turn lead to dehydration and electrolyte imbalances.
However, these electrolyte imbalances are rare if properly supplementing with electrolytes when sweating.
Vitamins are fat-soluble (vitamins A, D, E and K), or water-soluble (vitamin C, and B-complex).
Horses at maintenance usually have more than adequate amounts of vitamins in their diet if they are receiving fresh green forage and/or premixed rations.
Some cases where a horse would need a vitamin supplement include when feeding a high-grain diet or low-quality hay, if a horse is under stress (traveling, showing, racing, etc.), prolonged strenuous activity, or not eating well (sick, after surgery, etc.).
Most of the vitamins are found in green, leafy forages.
Vitamin D is obtained from sunlight, so only horses that are stalled for 24 hours a day need a supplement with vitamin D.
Vitamin E is found in fresh green forages; however, the amount decreases with plant maturity and is destroyed during long term storage. Horses that are under heavy exercise or under increased levels of stress also may benefit from vitamin E supplementation.
Vitamin K and B-complex are produced by the gut microbes. Vitamin C is found in fresh vegetables and fruits and produced naturally by the liver.
None of these are usually required in a horse’s diet.
Severely stressed horses, however, may benefit from B-complex and vitamin C supplements during the period of stress.
Finally, Minerals are required for maintenance of body structure, fluid balance in cells (electrolytes), nerve conduction and muscle contraction.
Only small amounts of the macro-minerals such as calcium, phosphorus, sodium, potassium, chloride, magnesium, and sulfur are needed daily.
Calcium and phosphorus are needed in a specific ratio ideally 2:1, but never less than 1:1.
Sweating depletes sodium, potassium, and chloride from the horse’s system, therefore supplementation with electrolytes is important for horses that sweat a lot.
Normally if adult horses are consuming fresh green pasture and/or a premixed ration they will receive proper amounts of minerals in their diet, except for sodium chloride (salt), which should always be available free choice.
Young horses may need added calcium, phosphorus, copper and zinc during the first year or two of life.
Stay tuned for the next column article when we will more thoroughly discuss different feeds and when they would be best for feeding your horse.
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