UNDERSTANDING THE BASICS OF FEEDING
Peter Waller. B.App.Sc. – Nutritionist, Compleat Feeds I O
It should be highlighted that when feeding horses we need to have at least a reasonable basic understanding of their digestive system including important areas of digestion and absorption and the physical limitations of the intestine in order to formulate a balanced ration.
It should also be emphasized that some sort of working knowledge in relation to various feedstuffs being used in the diet should also be understood so that we are able to differentiate between energy sources and protein sources and be able to formulate a ration where digestible energy and protein levels meet individual requirement specifications and are in correct proportion to each other. A ration where there is an adequate fat content, a ration where the mineral and vitamin balances are within ratio or requirement levels and at a level suitable for the class of horse being fed.
Without this understanding many mistakes will be compounded while you play with feeds and computer programs in an attempt to get your horse fed. Most owners simply opt to make use of premix rations – and unfortunately in more instances than not, the majority of these rations are simply not what they are claimed to be – they don’t make your horse look like it has been hit with a pretty stick nor do they deliver any other magical properties that are so often advertised.
Remember – we need to feed our horse for health and wellbeing. If this is done correctly then the natural coat shine and colour along with hoof condition, the overall wellbeing of the horse and its performance levels will naturally occur. I quite often get asked the question of ‘What can I feed to bring out the colour in my horse’? My answer is always the same – ‘Feed correctly to begin with. The colour you end up with is the horse’s natural enhanced colour and there is nothing you can feed to change it’.
THE PROCESS
After leaving the mouth where the foodstuff has been thoroughly chewed to break down longer or larger pieces as well as give a larger surface area and has been wet down with saliva, the food mass (bolus) enters the stomach. It is here that the digestion of some of the protein in the feed begins, nothing more. The stomach is simply a mixing bowl that has a need to be kept full. From here the food mass travels to and eventually through the small intestine. While the food mass is in transit through the small intestine, there is a considerable amount absorption of the nutrients contained in the feed (protein, and carbohydrate/starch, fats and oils, vitamins and minerals) as the small intestine is the primary site of enzymatic digestion.
The remaining food mass then travels to the caecum – the beginning of the large intestine, where fermentation of lower end fiber to VFAs (volatile fatty acids) takes place along with the fermentation of residual protein and starches that have by-passed the small intestine. Water is pulled from the system in order to further keep the food mass wet.
The food mass then moves on to the large colon where we have a further fiber to VFA process taking place, uptake of water into the feed mass to keep it thoroughly wet through and further fermentation of any residual starches.
The food mass then moves into the small colon where further fermentation of fiber to VFA and water uptake transpires, with any remaining components such as lignin then moving to the bowel and rectum. The nutrient composition and components are generally exhausted by this time, but it may be found through overfeeding of grains or the feeding of hard coated grains (eg: sorghum or wheat) or high fiber grains (eg: oats or sunflower seeds) without firstly being milled or otherwise mechanically altered, it is possible to find undigested grain in the fecal output.
You should be getting an understanding by now that the horse's hindgut is a complex organ.
A functional caecum (pronounced see-cum) is also highly beneficial because it produces significant amounts of the B group vitamin complex as well as volatile fatty acids (VFAs through the breakdown of fiber) that help meet the vitamin and energy requirements.
Also of note is the actual size of a horse's stomach. It makes up approximately 7%-8% of the overall intestine which in comparison to the physical size of the horse, is comparatively small being not much larger than a football.
It is because of this physical size of the stomach that the horse will inherently have its head down grazing for some 16-18 hours per day in order to keep that small stomach full. Because it is small compared to the horse's overall metabolic size, many classes of horses are not able to consume enough forage to meet their nutrient requirements. When this occurs we need to provide concentrates (processed grains etc.) and increase feeding frequency to support proper growth, development, performance and wellbeing.
BASIC NUTRIENTS
Water
This would possibly be one of the more overlooked nutrients in terms of importance. Water should always be available ad lib and in unlimited supply.
It is the nutrient essential for body form, (comprising ~65% of the horse’s body form) digestion and waste elimination. It plays a major role in the body's chemical reactions, the body’s cellular reactions and the transporting of nutrients and waste materials, thermoregulation (body temperature adjustment), joint lubrication, shock absorption in body cavities and joints, and blood and milk production.
Horses drink around 30 lts. of water per day (on average) depending on climatic conditions and workload. Lactating mares and hard working horses will consume up to 130 lts. of water per day in order to fulfill the demand created through milk production and metabolic losses through sweat, respiration and urination.
SOME TIPS
- Clean water buckets and troughs or tanks regularly.
- Remove green algae and other foreign material (dead birds in particular) from troughs.
- Water deprivation is more common in winter than during the summer because of sometimes freezing temperatures. However, my observations for an increased need for water during the winter months is also that the air does not contains as much moisture and the natural grasses and forages are normally killed off with frost and short regenerative periods with little sunlight (shorter days) and their DM (dry matter) content will have risen from anywhere from 26% to around 90%, thereby not supplying near the amount of moisture to the horse when grazing.
- Ensure that water sources do not freeze. We rarely see incidences of total freeze over in the more northern or western states for any length of time, but it can be a problem in the southern states that experience extremes in climatic conditions.
As with most species of animals, water deprivation is often a cause of death, and it occurs much more rapidly than with starvation. By the time you begin to realize the horse is severely dehydrated and depleted of body fluids it may be too late as the horse’s system (although critically dehydrated) will often fail to recognize the fact the animal is thirsty, and even if the horse is offered water it will fail to drink. It is therefore extremely important that a clean fresh source of water be supplied to horses at all times.
When a horse is short on fluid, the first sign of this imbalance may be colic; due to water being pulled from the gut to service more important functions such as cellular osmosis. If the animal continues to be short on water, more serious problems arise and death generally follows.
If dehydration is gradual, the first sign may be decrease in appetite and impaction; since there is little moisture in the digestive tract. Feces become few, dry and hard. (The horse won't eat, and passes little manure.) To prevent colic and more serious problems, you should make sure your horse has access to plenty of clean fresh water, and you should become aware of early warning signs of dehydration.
The pinch test can give a clue to the horse's fluid status. This involves pulling out a pinch of loose skin at the point of the shoulder, or more indicative, on the rib cage. When released, the skin should return right back into place immediately. If it takes 2 to 3 seconds and slowly sinks down then the horse is moderately dehydrated (loss of fluid in and around the tissue cells; the skin is less elastic). If it takes more than 5 to 7 seconds to sink back into place, the horse is more severely dehydrated and requires fluid intake immediately in small amounts on a regular basis.
Energy
Energy is not a nutrient per se. It is a measurement of heat released or expended in the breakdown of the various foods the horse eats. Some products have a higher energy release level than others and this comes through the digestion both in the small and large intestine of starch, sugars, oils of fats contained in the feed.
It does not matter if the horse is idle, in light, moderate work or undergoing heavy or intense training, lactating, growing, or in the last three months of pregnancy. All these classes of horses require energy in large amounts – even simply to maintain homeostasis (static life processes). In comparison with the average human who has a energy intake level of around 1200-1500 joules/day, the average horse requires around 68 megajoules (million joules).
Young growing horses or horses undergoing high levels of work and lactating mares have the greatest requirement for energy. This it is provided by the breakdown of starches, sugars and other soluble carbohydrates as well as from VFAs (volatile fatty acids) manufactured in the large intestine as a result of microbial digestion and breakdown of fibrous feeds.
Cereal grains such as corn, oats, and barley and other cereal byproducts (bran, pollard etc.) are some of the primary energy sources found in concentrate mixes. Vegetable oil is another extremely energy dense source with which to enhance energy intake. In fact oil contains about 2.25 more times more energy than the equivalent amount of oats.
In most cases, the greater the energy requirement of the horse, the greater the energy density (units of energy; Mj/kg of feed) of the concentrate is required.
For example, a horse in hard race training needs a more concentrated, energy dense feed than does, say, a Shetland pony standing about in a paddock.
Mature, idle horses and mares in the first 2 trimesters of pregnancy require less energy and therefore can mostly meet their energy requirement purely with unlimited supplies of a good quality hay or pasture provided they are also supplemented with a good quality mineral and vitamin mix such as Compleat Feeds BALANCE. In young, rapidly growing horses, horses at work and lactating mares, the hay fed (no less than 50% of the ration) should be supplemented with a concentrated energy source to meet their energy requirements, such as the use of a vegetable oil (not olive oil as it is not palatable to horses) in the diet to make the ration more ‘energy dense’ without having to overload the horse’s digestive system with high amounts of grains or concentrates. Compleat Feeds Equi-Shine E blended performance oil is a recommendation here to ensure that not only are energy levels being met or enhanced, but the Omega 3 : Omega 6 balance is also being kept in check so the horse gains maximum benefit through the supplementation of this product.
Protein
All horses have a particular requirement for protein. It must be noted however that horses are not protein digesters as such and not reliant on protein as their major source of nutrient intake regardless of what the feed bag label may tell you or what your previous thoughts on the matter are.
The amount of protein required is governed solely by their performance levels.
If their protein requirement was similar to that of a carnivore or omnivore we would simply feed them on steak, eggs and cheeses. Their requirement is for a high quality protein rather than protein of lesser quality.
When we are describing protein quality it should be understood that protein is broken down into its various amino acid profiles and that the overall matrix of amino acids (protein) is used as the ‘building block’ of muscle and in the synthesis of various other body tissue, and that protein is made up of 22 amino acids (AAs) that are the ‘building blocks’ for protein.
Most of these AAs are synthesized in the gut. However there are 10 amino acids we must supply to the horse (essential AAs). Protein will vary in amino acid composition, and the term ‘protein quality’ is a relative reference to the amount of the essential amino acids, especially the limiting AAs (lysine, methionine, and threonine) contained within the protein. Eg: Soybean meal, canola meal or good quality lucerne hay. A way of determination is – the higher the Lysine level, the higher the protein degradability, the less Lysine, the lower the degradability as a protein source.
Protein requirements vary for different classes of horses. Young, growing horses have a higher requirement (14-16%) for protein because they are developing body tissue such as muscle at extremely rapid rates, therefore the requirement is more.
Mature horses have a lower requirement for protein (around 8-10% of the ration) than young horses since mature horses need protein for maintenance or repair of body tissue rather than growing new tissue in every area. So, quality rather than quantity is the secret when it comes to providing protein. Choose a source that has high levels of Lysine (Canola meal, soy meal) in order to get the most from your ration.
Note: - Horses with increased exercise levels do not require greater amounts of protein than horses not in training. They lose a small amount of nitrogen in their sweat when working, but the additional grain fed to meet the performance horse's energy needs will more than adequately provide the increased nitrogen requirement without increasing the percent protein in the diet.
When protein is fed beyond what the horse requires it really is not harmful to the horse, but is wasteful; as the body uses it as an energy source and excretes the unused nitrogen in the urine, and protein is a very expensive energy source.
Both forage and concentrate portions of the horse's diet will supply protein. The quality of hay or forage fed will greatly influence how much protein is required when feeding the concentrate. Good quality legume hay will contain from 14-18%, (and sometime up to 22%) CP. High quality grass hay will contain between 7.0-12% CP. Cereal grains will also supply protein in the diet. But depending on the class of horses being fed, the forage component of the diet may not be able to meet their protein requirement. Cereal grains will range in protein content from 8.0-12.0%.
To meet the protein requirement of the young, growing horses you will need to use a protein supplement. (Soybean meal is the most common protein supplement used in horse rations.) Other protein supplement sources are available such as linseed meal, cottonseed meal (not recommended due to gossypol content), dried skim milk or commercially prepared protein supplements which may contain a combination of the above ingredients.
Minerals
Minerals are needed by the horse's body for various purposes, ranging from serving as components of the horses skeletal system to maintaining nerve conductivity, muscle contraction and electrolyte balance.
Calcium & Phosphorus. These two minerals comprise about 70% of the mineral content of the horse's body and make up the greater proportion of skeletal bone formation, therefore they need to be supplied to the horse in the greatest amount and are (or should be) of most concern when formulating horse rations.
Horses are more likely to suffer from a lack of calcium and phosphorus than from a lack of any other mineral.
Proper levels and ratios (Ca:P - Ideally calcium and phosphorus should be fed at a 1.2-2: 1 ratio) of these two minerals are very important for normal development of bone in the skeletal system. If inadequate levels or the incorrect ratios are supplied, skeletal structural deformities may well be the result.
Never feed inverted Ca:P ratio (higher levels of phosphorous than calcium) because it may lead to a condition known as ‘Bighead’ or NSH (Nutritional Secondary Hyperparathyroidism) and do irreparable damage to the horse. Remember, if supplementing your horse with Calcium Carbonate or Dolomite, to balance it up to the required ratio with Phosphorous either through feeding extra grain, or grain by-product, OR, better still, where possible, use DCP (DiCalcium Phosphate) as the supplement instead of dolomite or straight calcium; as it contains 23%Ca:18% P (a natural ratio of 1.27:1) giving no further need to supplement with anything else.
Always provide salt to the horse as free-choice. Salt is composed of sodium and chloride which are important in maintaining electrolyte and acid base balance. It is most commonly given by provision of a trace mineral salt block as free choice. Personally, I am not inclined to provide my own horses with these commercial blocks as they are really a very expensive way to provide salt to a horse as the amount of mineral contained in these blocks is minimal to say the least. If you do feel the need to provide one of these blocks for your horse, ensure it is a mineral block manufactured especially for horses and not a ruminant block as many of these cattle blocks contain Rumesin, which is extremely toxic in small amounts to horses. Over consumption of salt is usually not a problem if free choice and fresh water is available.
Copper and zinc have been implicated in metabolic bone disease. Although their exact role is not clearly understood, it is recommended to include copper in the concentrate at 30-50 ppm and zinc at 80-120 ppm. The over supplementation of copper is a dangerous procedure, especially if following some of the more popular so-called ‘natural’ methods of supplementing with copper sulfate as it interferes with the uptake of various other minerals and vitamins and renders them useless. As a matter of further interest, humans have committed suicide on less than 11mg of copper sulfate. Compleat Feeds use copper only in the Broodmare & Stud mix and both Foal # 2 and Foal # 3 mix at the rate of 250 mg/tonne (0.25 g/tonne) of feed.
Selenium is also a trace mineral required by the horse. Most naturally occurring feedstuff will have enough selenium to meet the horse's requirement. (Selenium is extremely toxic when fed in quantities above recommended levels.) However, most commercial feeds will contain selenium at 0.1 ppm. Do not top-dress it as a mineral supplement.
Combined with Vitamin E, it has been suggested that it may assist in the prevention of ‘tying-up’, however it is known the combination of vitamin E and Se does play an important role in the prevention of white muscle disease.
Vitamins
Strangely enough, Vitamins A, D and E are the most common that are added to horse rations. I say strangely because these are 3 of the 4 vitamins that are fat soluble. This means they are accumulated in the horse by being stored in the liver and are not essentially required on a daily basis.
Vitamin A is the vitamin most likely to be marginal in most horse diets. The natural source of Vitamin A is beta-carotene, which occurs in green forages and properly cured hays. As long as the hay source has a green color and is leafy, then it will probably be more than adequate to meet the horse's Vitamin A requirement. Vitamin A functions in the maintenance of epithelial integrity (eye), normal bone metabolism and is very important for night vision. A deficiency in Vitamin A may result in night blindness, upper respiratory infection, brittle bones and possibly many other deficiencies. One reason to supplement Vitamin A is that horses are not very efficient in converting beta-carotene to active Vitamin A.
As a fat soluble vitamin, it can be stored in the liver for considerable periods of time.
Vitamin D is very important in the normal absorption and utilization of calcium and phosphorus. It also functions in the absorption of several minerals for bone deposition.
Vitamin D is converted from precursors through a series of reactions in the skin stimulated by sunlight. Rickets in young horses and osteomalacia in older horses are the two most common symptoms of Vitamin D deficiency.
Giving large doses of Vitamin D should be avoided as toxicity may occur resulting in calcification of soft tissue. Natural sources of Vitamin D occur in sun-cured hay and cod liver oil.
The vitamin D is naturally occurring through sunlight, and as long as the horse is not rugged from head to toe and confined to a stable during daylight hours, will receive enough vitamin D from this source without further supplementation.
Vitamin E is found in sufficient quantity in most natural feedstuffs (pastures and grasses) in levels that are enough to at least meet the horse's requirement.
Roughages, cereal grains and especially cereal germ oils are high in Vitamin E, particularly wheat germ oil. Vitamin E is implicated in many physiological functions in the horse body. It maintains membrane stability and red blood cell integrity. Selenium and Vitamin E interactions may play a role in treating and preventing “tying up,” and possibly in assuring normal reproduction.
It is believed that the micro flora in the caecum will synthesize adequate amounts of B vitamins for absorption to meet the horse's requirement. Many of the B vitamins function as coenzymes in energy pathways and it is questionable whether adequate amounts of B vitamins are synthesized by the horse to meet the needs of young, rapidly growing horses and horses at high work levels. Although the water soluble B complex vitamins may not be commonly supplemented, with an inclusion in performance horse rations it will fortify their diet and assist in carbohydrate digestion and various interactions in the nervous system.
Remember that horses need long stem roughage in their diet for normal digestive function. Horses fed hay or those on pasture are more able to maintain gastro-intestinal tract normality, experience less colic and are less prone to developing annoying stable vices such as crib biting or weaving when compared to horses not receiving a long stem roughage source.
Feed horses hay that is bright colored, leafy, harvested in an early stage of maturity and free from mold or foreign matter.
Common hays fed include lucerne, timothy and clover, though Rhodes grass/lucerne mix is becoming more readily available on the market as well. You can also combine these hays for feed. When timothy and lucerne are used together, lucerne will usually be fed as a nutrient source and timothy as the roughage source.
Use pastures to their utmost in a feeding program. Many classes of horses can meet their nutrient requirements on pasture alone, if the pasture is managed and stocked properly. Mature, idle horses, barren mares and mares in the first 2 trimesters of gestation on well managed pasture should require little or no supplementation.
Remember that horses are individuals and should be managed as such. By knowing the nutrients they need and their function, you will find the art of feeding horses much easier and simpler.
Also please remember as a consulting nutritionist for Equine Excellence Magazine, I am always available to answer any questions or help solve problems you may be experiencing with your feeding regime. As is the motto of Compleat Feeds – Always with the horse in Mind.
