Trainer Magazine

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Time for a re-think? Why do we deny a horse water and fibre before a race?

NUTRITIONWebmaster

Removal of fibre and water intake before a race are supposed to enhance performance in Race Horses… Surely this is not sound practice, let alone science. No sensible, modern day athlete would go out of their way to cause discomfort in their digestive system and thereby reduce performance, let alone remove hydration. Perhaps the racing industry should look outside their field of view and take a leaf out of the endurance horse world. In this field of horsemanship, horses are fed just before and even during competition and hydration of the horse is paramount. Common sense says that a happy and comfortable horse will give us its ‘all’. Perhaps now is the time for a bold trainer to take this on board. The following is a more scientific rational behind my thinking.

The evolution of the horse into the animal we know today has meant the development of a very specialised digestive system. The proportionally huge hind-gut indicates the importance of fibre/forage in the equine diet. The specialised stomach has evolved to cope with a nearly continuous intake of fibrous plant material, so that (unlike the stomachs of omnivorous and carnivorous animals) the pyloric sphincter allows a ‘trickle’ of partly digested material into the small intestine. This function may cause a problem for horses fed a high level of concentrates as this ‘trickle’ mechanism can allow food to pass through the sphincter, before sufficient digestive processes have taken place. Also the acid level in the equine stomach is relatively high, as it has evolved to start the breakdown of cellulose in plant material, ready for digestion.

It has been suggested that inadequate provision of fibre in the diet may be a reason for many cases of stomach ulcers in horses. For optimum health and performance all horses require a balanced supply of :- Fibre – 1) indigestible fibre – for gut health and motility and 2) digestible fibre for nutrients and energy – the cellulose of plant material is broken down by colonies of microbes in the hind-gut into ‘complex’ carbohydrates, producing Volatile Fatty Acids which are absorbed into the blood stream, transported to the liver and converted into fat. This fat can be utilised by the body cells for energy or stored as adipose tissue until further energy is required. The process of fermentation and absorption of volatile fatty acids continues for many hours, so that horses may draw on the stored energy as required.

Good quality hay and pasture can provide much of the essential nourishment required for general maintenance and health, always providing that a balanced supply of micronutrients is fed. For horses in strenuous work, high energy fibre sources such as alfalfa chaff and sugar beet shreds can be a valuable part of the ‘short’ feed. The provision of adequate dietary fibre, in the daily diet, satisfies the equine ‘trickle’ feeding system and also the physiological and psychological need to chew.

Starch & Sugars – ‘simple’ carbohydrates for an energy supply – from oats and micronised cereals, Care has to be taken with quantities fed, as cereal overloading has been considered as a possible ‘trigger’ for problems such as ‘set-fast’, laminitis, azoturia etc. The choice and balance of cereals in the diet is also important, as some horses have been found to show an apparent intolerance to barley, exhibiting skin eruptions, filled legs and/or excitable ‘mood swings’. Cereals are broken down into their component glucose molecules in the small intestine and absorbed into the blood stream.

This ‘blood sugar’ can be directly utilised by the muscles as a valuable ‘fast release’ energy source for short bursts of strenuous work or stored in the muscles or the liver as glycogen. During prolonged exercise a problem found to be associated with fatigue – hypoglycaemia (low blood sugar) – may be avoided by the provision of sugars such as molasses in the diet. Vegetable Protein – for tissue repair and development of almost all body constituents; Cereals contain a very small percentage of protein which is digested in the small intestine. Soya beans, an excellent source of quality protein, are also digested in the small intestine; providing the 22 amino acids commonly recognised as essential in the horse’s diet. Most importantly the limiting amino acids lysine and methionine, as they are likely to cause metabolic problems if in short supply. Methionine is classified as an essential amino acid, it helps lower cholesterol levels, reduces liver fat protects the kidneys and regulates ammonia formation, also a natural chelating agent for heavy metals.

Certain amino acids are necessary for the metabolism and utilisation of energy. It is recommended that care should be taken to supply a correct balance of protein for horses under six years of age, as they are still in the growth and body building stage and will have greater requirements for protein and the associated, necessary micronutrients than the mature horse. Lysine is the amino acid involved with growth as are the minerals calcium, phosphorus, copper and zinc for the strength and integrity of cartilage and bone. However overly high intakes of protein can lead to an increase of urinary ammonia producing and/or aggravating respiratory problems for the stabled horse. Also, over feeding protein can cause an increase in the requirement for water possibly leading to a certain amount of dehydration and at least very wet beds - with a resulting increase of ammonia! . Fats/Oils – 1) as an energy source, 2 ¼ times the energy of carbohydrates per unit weight. 2) as an insulating layer of subcutaneous fat and 3) for development and maintenance of cell membranes. It is thought that fats may prove valuable in increasing the performance of horses at sustained submaximal exercise by providing a higher energy density diet, with the risks of carbohydrate overloading likely to be reduced.

The horse conditioned to an intake of oil in the diet will be able to accept more demanding training sessions, leading to increased fitness and performance . Made up from ‘chains’ of fatty acids, linoleic, linolenic and arachidonic acids are considered to be important for the horse.

If the blood glucose and muscle and liver glycogen energy stores have been depleted then the body will convert to fat oxidation for metabolic energy. – from ‘ The Scientific Rational for High Fat Diets for Equines’ Deborah M Lucas MSc, CBiol, MIBiol, R.Nutr. Minerals – almost every body process requires a correct supply (the feral horse fulfilled requirements from a variety of herbage grown in different soil types).

Minerals rarely act on their own, but interact in groups and with Vitamins, so that a deficiency or excess of one may affect many body processes; for example, research suggests that excessive iron intake may cause a type of metabolic corrosion affecting both respiratory tissue and working muscle. Also a balanced supply of trace elements such as selenium, copper, zinc and manganese along with vitamins E and C is advisable, to protect cell membranes from ‘free radicles’ and help control ‘oxidative’ stress for horses in heavy exercise, under stress and when travelling etc. Vitamins – as above almost every body process requires a correct supply.

Vitamins rarely act in isolation but interact with other vitamins and with minerals. For optimum health and performance a correct and balanced supply is essential. For example – the normal requirement for Vitamin K (important for the blood clotting mechanism) can be met through microbial digestion in the gut, if quality forage is supplied; but a deficiency has been considered to be a cause of pulmonary bleeding and internal haemorrhage, so it should be supplied in the diet of the stabled, working horse. The important B complex vitamins can also be manufactured by the gut microbes during the digestion of forage, but additional dietary supplementation will be required for stabled horses in work . The correct storage of Vitamins is vital as they are sensitive to heat, light, moulds and oxidising agents.