Principles of ration formulation

Energy
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The energising components of horse feed is vital for the bodily functions of the horse. Both the musculoskeletal system and the body’s internal processes require energy as ‘fuel’.

The ability of horse owners to adapt feed rations according to the needs of the horse is crucial for its performance and well-being. Let us talk about some important aspects that affect the energy needs of a horse.

Sources of energy
Fibrous energy: The primary source of energy in the diet of a horse consists of forage (i.e. grass, hay, silage, straw, etc.). The energy in the forage feed is absorbed in the large intestine of the horse by way of a microbial fermentation of cellulose. Carbohydrates: Starches and sugars – occurs naturally in hay but also added in the form of for example molasses and cereals. Fat: Found in, for example, oats and also added in the form of vegetable oils.

Increased energy requirements
Intensified exercise and training will always lead to an increased demand for energy. Most horse owners are aware of this and learn how to adapt the supply of energy to the energy needs of their horse. There are also other

– although often overlooked – situations when there is an equally high demand for energy. Cold weather conditions, for example, will always lead to an often underestimated ‘upshift’ in the horse’s need for energy. Many horse owners fail to understand the chill factor of wind and rain combined which can only be counterbalanced by an increased intake of energy. Failing to increase the intake of energy will lead to the horse breaking down stored energy supplies, i.e. fat, in order to produce heat. As a consequence, the horse starts to lose its heat insulating layer of fat which, if the cold weather conditions continue, creates a vicious circle. Other energy-consuming processes include gestation, lactation and growth. The energy needed in the final phase of gestation and the significantly increased demand for energy during lactation are often underestimated. The energy need of a lactating mares is considerably higher than that of a non-lactating mare. The need for extra energy is especially great during the first three months after foaling. It is estimated that a mare’s need for energy doubles during lactation compared to in her first few months of gestation (first trimester of gestation).

Different energy concepts
In Sweden, energy is measured in MJ (megajoules). We will talk about how different countries measure energy later on. First, let us look a little closer at different ways of defining energy. Gross energy – the total amount of energy in the feed consumed. Digestible energy (DE) – the gross energy of the feed minus the energy content of the faeces. Metabolisable energy (ME) – the digestible energy minus energy excreted in urine and as combustible gases. Net energy (NE) – the metabolisable energy minus the energy used when eating and digesting food. In Sweden, the energy content of a feed is measured in MJ metabolisable energy (ME). Denmark and Norway on the other hand measure energy need and food content in NE (net energy) and FU (food units) while in France, the food content is measured as net energy (NE). In Germany, the United Kingdom and the US, the definition of digestible energy (DE) is used. In the US and certain other countries, the definition of Mcal (megacalories) is also used to measure energy. Sometimes the energy content of a feed is specified as energy per kilogram of feed or per kilogram of dry matter. The above shows the importance of horse owners who chose to import their horse feed from abroad to be attentive to the way in which the content of energy is declared. Crude protein is usually not declared as digestible energy (DE) but as crude protein in %.

Protein
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Proteins constitute the parent material in all body tissues. The chemical composition of these proteins may vary through different combinations of compounds called amino acids. Some amino acids are absolutely essential for the functioning of the body and need to be added on a daily basis. These are generally referred to as essential (as in essential to life) amino acids. Lysine and methionine belong to this group of amino acids. The need for protein is at its highest when the horse is growing, carries a developing fetus or is lactating. ‘Maintaining and repairing’ the body tissue of an adult horse requires a considerably smaller amount of protein. Older horses, however, often have a reduced ability to absorb and utilise protein and may need a protein supplement.

Careful consideration ought to be given to the protein content of the concentrate feed compared with that of the forage feed. Forage that is harvested early usually has a high content of protein. A dry spring usually means an early harvest of fresh spring grass and, as expected, a forage feed with a very high protein content. Consequently, there is good reason to have your forage feed analysed before taking the protein content of your concentrate feed into careful consideration. Forage feeds with an extremely high content of protein are unsuitable for the horse as not only are they low in fibre but they are also too rich in protein.

Excess protein can lead to gastric problems and deterioration of the general health and performance of the horse. Overfeeding of large quantities of highly digestible protein may, in severe cases, lead to diarrhoea and life-threatening disturbances in the large intestine caused by the growth of a specific bacteria called (Clostridium Perfringens).

What about the quality of the protein?
In this context, we would also like to stress the importance of the protein quality. The feed you give your horse should include protein with a composition of amino acids suitable for horses. The protein that is not used is excreted from the body, a process which in itself requires energy. Many horses are deprived of the protein they need to develop muscles as a result of not being able to utilise the protein provided in their feeds.

Different feeds contain different qualities of feed. The protein found in normal oats is of moderate quality while for example maize, owing to its composition of amino acids, is a relatively poor source of protein for horses.

KRAFFT’s range of products contains only high-quality protein for efficient digestion and utilisation by the horse.

Protein deficiency
The most common signs of protein deficiency in horses that are not pregnant or lactating include the loss of muscle mass and difficulty gaining muscle mass. Poor muscle definition in a horse is often caused by the horse not getting enough protein or the wrong type of protein in its diet. In some cases, it is a question of the horse not being provided with the right amount of energy. The horse then ends up ‘stealing’ protein as an alternative source of energy. As a result, there is not enough protein to build up muscle mass. A poor muscle definition should always prompt a thorough examination of the feed given. When examining the feed rations of your horse, it is important that you have an idea of’ the nutritional value of the forage feed – and the only way of getting this is to have it analysed.

Fat
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Fat usually occurs as triglycerides where two fatty acids are linked to glycerol. This is split into free fatty acids and glycerol which is absorbed in the small intestine of the horse. Just like starch, excessive amounts of fat that cannot be absorbed by the small intestine continue to the large intestine where they may cause unwanted fermentation.

Fat provided in the feed is broken down by digestive enzymes in the pancreatic juices, otherwise known as lipase. In order for this process to work, emulsifiers in the form of bile are needed. The horse does not have a gall bladder and bile is added all the time. Hence, the horse is not equipped to digest large quantities of fat over a short period of time. Adapting the horse to digesting fat should therefore be a slow process with a maximum amount of 70-100 g fat per 100 kg of body weight and feed which is equivalent to max. 0.5 kg of fat per feed for a 500 kg horse.

The horse uses fat as a source of energy and too much fat may lead to obesity. Fat contains more than twice as much energy as carbohydrates. For the hard working horse that needs a lot of energy, supplementing its feed with fat is beneficial as fats and carbohydrates are digested by different digestive systems. Fat is also used to maintain a glossy coat and to help horses loose or gain weight, if needed.

Fatty acids such as linoleic acid (omega-6), oleic acid (omega-3) and arachidonic acid are so-called essential acids, i.e. essential to life. How much fat a horse needs is still not known, nor how much of the different fatty acids it needs. According to current recommendations, dry matter feeds should consist of at least 0.5 % of oleic acid. For most horses, the recommended proportion of oleic acid is provided in their forage feed.

Extra fat are easily added in the form of vegetable oils. Vegetable oils have a different fatty acid composition but the content of energy is basically the same. Most vegetable oils that are fit for human consumption can be fed to a horse. When adding extra fat/oil to your horse’s diet, the need for vitamin E will also increase.

Fibres
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Fibre is a structural carbohydrate , also known as crude fibre. Dietary fibre includes cellulose, hemicellulose and ligning. The horse is unable to break down ligning but the other two substances are broken down by the microorganisms in the large intestine.

The microbial fermentation in the large intestine of the horse is vital as around 75 % of the energy supplied in forage based feed rations is produced through the fermentation of fibres into short-chain fatty acids. The amount of energy supplied will drop slightly when the horse is given more concentrate feed. This very sensitive system can easily get disrupted by rapid feed changes. In order to function optimally, the microorganisms must have an even and continuous supply of fibres. Fibres take longer to ferment than for example starch which helps fill up the gastrointestinal system, a natural process for the forage digesting horse. The volume of the intestines also helps maintain the fluid balance and hydration of the horse. An insufficient amount of fibre will not only have an adverse effect on the digestive system of the horse but also on its general health and well-being.

How much fibre a horse needs has never been clearly defined but the recommended minimum amount of forage feed a day is 1 kg of dry matter/100 kg body weight – though preferably 1.5-2 kg a day. It is important to know how much dry matter the forage feed contains as this varies widely depending on the harvesting method used.

Fibre is largely provided in the forage feed but there are also other raw materials containing relatively large amounts of fibre such as oat bran, wheat bran, beet pulp and lucerne (alfalfa). Cereals, on the other hand, are low in fibre.

Sugar
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Decomposition of sugar

Sugar is a non-structural carbohydrate. Simple sugars are called monosaccharides and when two of these are joined, they become disaccharides. In order to be called sugar, the compound sugar must contain less than 10 monosaccharides. In nature, sugar comes in the form of glucose and fructose. The sugar found in forage is mainly glucose. In the horse, the disaccharides are digested by enzymes and turned into monosaccharides that are then absorbed by the small intestine. Fructose is converted into glucose in the horse’s liver. Sugar is highly digestible and quickly raises blood sugar levels.

Sugar in horse feeds
Sugar comes in many different forms. Forage feeds contain a varying amount of sugar depending on composition, harvest time and storage. Most laboratories include sugar in their analysis of forage feed. The average quality hay contains about 10 % of sugar in dry matter form while silage contains a little less as some of the sugar is consumed in the ensiling process. Raw materials with a high proportion of sugar include molasses and molassed beet pulp. Molasses contain around 60 % sugar in dry matter content. Cereals and lucerne have a lower content of sugar – only a few percent. Processed horse feeds contain around 3-5 % sugar, depending on the area of use.

Sugar as a source of energy
Sugar and starch are sources of energy that also contribute to the palatability of the feed. The horse is adapted to eating sugar and has no problems digesting controlled amounts of sugar. As mentioned above, its most natural diet of grass contains around 10 % sugar.

Too much sugar
Many equine diseases and ailments are linked to the intake of sugar and research on the effects of sugar on the health and well-being of the horse is ongoing. Horse owners wanting to reduce the intake of sugar should feed silage rather than hay as a lot of the sugar in silage is consumed during the ensiling process.

Starch
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Decomposition of starch
Starch is a non-structural carbohydrate (polysaccharide) made up of glucose molecules. There are two types of glucose molecules – amylose which is linear and amylopectin which is branched. Starch is broken down or decomposed by the enzyme amylase. In the horse, decomposed starch (glucose) such as glycogen is stored in the liver and muscle mass. The low concentration of amylase found in the pancreatic juice is used in the small intestine to break down starch. Consequently, the horse is not able to break down large amounts of starch at a time, no more than 150 g starch/100 kg body weight and feed. A horse should not be getting more than 500 g starch a day per 100 kg body weight (distributed over several feeds). Any undigested starch will continue to the large intestine where it may cause problems in the form of unwanted fermentation throughout the rest of the digestive process. An enzymatic breakdown of starch in the small intestine provides the horse with more energy than a microbial fermentation of starch in the large intestine.

Starch in horse feeds
Starch is, among others, found in cereals. Since the structure of starch varies in different types of cereals, the digestibility of different cereals varies too. However, it is possible to influence the digestibility of the starch by, for example, subject the cereal kernel to steaming. The starch found in oats is highly digestible compared to the starch found in, for example, barley and maize which are better processed. This may be one of the reasons why some horses feel warm after having consumed oats. Starch is easily digested and quickly absorbed in the small intestine and raises blood sugar levels. Forage feeds and raw materials such as beet pulp and lucerne (alfalfa) have a low level of starch. Muesli mixes usually contain more starch than pelleted feed because it is simply easier to use fibre-rich ingredients in the production of pellets. Fibre-rich raw materials often have a more ‘floury’ consistency and hence, must be pelleted before being used in muesli mixes. As a result, starch levels in different feeds may vary greatly and it is therefore important to find out the content of a feed.

Starch as a source of energy
The horse uses starch as a source of energy based on its high digestibility and suitability for explosive muscular activity. However, in order to function optimally, the horse also needs energy from other nutrients. For more information about this, refer to the sections above on fat and fibre.

Too much starch
Any starch that is not absorbed by the small intestine will continue to the large intestine where it may cause problems in the form of unwanted fermentation. This, in turn, could lead to diarrhoea, among other things. Accordingly, it is important to follow the recommendations given and regularly check the faeces and general condition of horses on a starch-rich diet.

Minerals and trace elements
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Minerals consist of a group of substances that are hugely important for the chemical composition of the body and functioning of various organs. Minerals are usually divided into macro minerals and micro minerals. The latter of the two is often referred to as trace elements. In the group of macro minerals are included calcium, phosphorous, magnesium and sodium, potassium and sulphur. In the group of trace elements are included iron, copper, iodine, cobalt, manganese, selenium, zinc and molybdenum.

As evident from the above, this is a large group of substances. The absorption of minerals is to some extent regulated by the horse itself, a regulating mechanism that is controlled by hormones. There is also interaction between the different minerals. A surplus or deficit of a substance may, for example, affect the ability to absorb another substance. The fact that the horse to some extent self-regulate its absorption of minerals does not, however, mean that the horse owner no longer needs to think about the mineral balance of the feed given. There is still a risk of mineral deficiency despite the horse self-regulating its intake of minerals. Too much of one specific mineral may result in mineral metabolism disorder. Hence, it is important to get the balance right.

The ratio of calcium to phosphorous is often discussed in the context of equine feeds. A delicate balance exist between the two. The problem is that the ability to absorb phosphorous can vary greatly from horse to horse and also, from one time to another. The bacterial flora in the large intestine is crucial for the absorption of phosphorous. In fact, the absorption of phosphorous is largely dependent on the bacterial flora. In order for the balanced ratio of calcium to phosphorous as administered in the diet to be correctly absorbed, the large intestine must function properly.

Vitamins
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Vitamins are a group of substances found in a number of vital processes in the body of the horse. These vitamins interact, among others, with another group of substances called enzymes. Most of the vitamins needed, the horse cannot produce itself and these must therefore be added to the diet. Here is a short summary of the most common vitamins.

Vitamin A
Vitamin A plays an important role in the protection and generation of mucous membranes. It also affects fertility, metabolism, immune system and night vision.

Vitamin D
Vitamin D affects the calcium metabolism which is important for the normal development and maintenance of the skeleton. Under the influence of sunlight, the horse is able to self-produce vitamin D.

Vitamin E
Vitamin E prevent cells in the body from breaking down due to the influence of so-called free radicals, that is, substances formed during muscular activity. During this process, vitamin E interacts with selenium. Vitamin E is also promotes immune system function in the horse.

Vitamin C
Vitamin C is seldom given as a supplement to horses. Some studies have shown vitamin C to have a certain function in the fertility of both stallions and mares.

Vitamin B
The vitamin B complex contains vitamins that affects the horse’s conversion of energy, production of red blood cells, production of important amino acids and nervous system functions. Most of the B complex vitamins are produced by microorganisms in the large intestine of the horse. A disturbance of the normal intestinal microflora owing to, for example, stress and/or surplus starch may cause of vitamin B deficiency.

Biotin
Biotin is part of a number of processes such as the metabolism of carbohydrates, fat and protein. It also plays an important role in the maintenance of the skin and mucosal surfaces. According to some studies, there is also a probable link between biotin and the hoof horn. Biotin is produced by the microorganisms in the large intestine.

Water
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Water must invariably be seen as a type of feed and the quality of the water given to horses should always be good enough for human consumption. Just like humans, horses consist mostly of water. This demands careful consideration by the horse owner and any fluids lost must immediately be replaced!

Remember too to check the quality of the water as polluted waters are every year a major cause of decreased performance. The quality of the water can be affected by bacteria, mould spores or other microorganisms. Poor quality drinking water does not always give any external symptoms. However, the immune system of the horse will be mobilised to combat these and any other harmful organisms. Always clean your water tubs and buckets on a daily basis.

And remember to check and clean automatic water feeders too!
Automatic water feeders are more often than not the reason for dehydration in horses. Automatic water feeders should provide at least 8 litres of water per minute. If this is not the case, the horse often ‘tires’ of pushing down the valve lever. Fill up the water feeder, put a bucket underneath and then press the valve lever for 1 minute for extra water. Note that the water feeder must be filled to the rim before beginning to time 1 minute of extra water. Then measure how much water you have in the bucket, there should be at least 8 litres.

How much does a horse need to drink? Here follows an easy way in which to find out how much your horse needs to drink every day. The figures shown are in accordance with the feeding recommendations of the Swedish University of Agricultural Sciences in 2013.

Maintenance – 5 litres per 100 kg horse

Light to medium work – 7 litres per 100 kg horse Hard work – 10-15 litres per 100 kg horse Lactating mares – 8-10 litres per 100 kg horse

Naturally, all horses have their own individual character traits and like us humans, some are better drinkers than others. If your horse is drinking a little bit less than the recommended daily amount but is otherwise behaving as usual, then there is nothing to worry about.

Salt & electrolytes
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Assuming that the horse has free access to water, a simple salt block/lick will provide it with the salt it needs. Salt given to horses should preferably be a pure type of salt such as vacuum salt, which is the purest type of salt available. When sweating a lot, the horse loses large amounts of salt which must quickly be replaced, especially before exercise or a competition. Salt plays a key role in the horse’s regulation of thirst. A salt block/lick is then often insufficient.

All horses need a supply of salt even if the need for salt varies significantly from horse to horse and is also season-dependent. The variation seen in different horses depends among other things on how much the individual horse sweats. Giving the horse free access to salt does not put it at risk of excessive salt intake as the horse’s kidneys will excrete any salt that is not utilised. A horse usually needs around 10-30 g of salt a day.

Foals may get diarrhoea from licking salt off a salt block/lick and young foals get the salt they need from the lactating mare. While the foal is still suckling, it is recommended that the stone block/lick is put in a slightly elevated position within reach of the mare but without reach of the foal. Once the young foal is ready for its own feed rations and is no longer suckling, it may be given free access to a salt block/lick.

Consequently, it is not just fluid that the horses loses when sweating but also, electrolytes and salt. Electrolytes is a generic term for substances affecting the regulation of body fluids. Apart from salt (also called sodium), potassium is another substance in the group of electrolytes. A healthy horse will retain the electrolytes it needs but a horse that sweats a lot or is regularly subjected to hard work may need help to regain the electrolytes that have been lost. Electrolytes help the horse to quickly recover following hard work and is usually given to horses in hard work that need more than salt. Horses producing runny wet faeces may also need a supplement of electrolytes.