Nutrition Requirements for Exercising Horses
In today’s industry nutrition requirements are extremely important, where seconds mean the difference between 1st and “also ran” at the track, our equine athletes must retain a competitive edge. Renewed interest in research about the performance horse’s nutrient needs has allowed horsemen to feed the athletic horse more scientifically than ever before to maintain that edge.
Ration Analysis of Energy Containing Feedstuffs
Feedstuffs not only differ in energy concentration, but also in the concentration of starch, fat and fiber. For example, corn is expected to contain about 1.6 Mcal DE/pound, 70 percent starch and 3 percent fiber, while oats are expected to contain around 1.3 Mcal DE per pound, 45 percent starch, and 10 percent fiber. These relative concentrations are useful when you analyze the total intake of different rations fed at levels to meet the same nutrician requirements.
Both fat and nonfibrous carbohydrates can be efficiently used as energy substrate, but the ability of each to replenish different fuels for muscular exercise is specific -- that is, fat cannot produce glucose. The added fat diet has the benefit of supplying larger amounts of a safer nutrition in smaller ration amounts, thus aiding as a guard against weight loss from net negative energy load during intense conditioning programs. Whether or not athletic performance is negatively affected by the lower starch content of the added fat ration depends on the type of athletic performance, the intensity of exercise and probably individual horse differences in utilizing different substrates. The exact nutritional requirements for different energy components of rations designed for horses performing different types of exercise are not fully agreed upon by nutritionists.
There are several considerations for supplying nutritional requirements for exercising horses. First, ideal body weight and condition for maximizing performance varies between individuals and conformation types. Most successful trainers condition horses into fitness and body condition through exercise programs while maintaining generous supplies of energy instead of restricting energy intake to keep body weight off. Nonfibrous carbohydrates supply the horse with a source of glucose, the energy source for anaerobic exercise. Large amounts of nonfibrous carbohydrates at a single feeding increase the incidence of colic and founder, so three-a-day feedings are recommended when you feed horses large quantities of grain.
Fat supplies large amounts of energy per unit weight and is used as an energy source for aerobic exercise. Fat may have its best nutritional benefit by maintaining the horse in energy balance during the long hours of conditioning, thus sparing the amount of glucose containing compounds in the muscle for the day of performance. Mixed grain diets with and without added fat have been used successfully to meet nutrition requirements for exercising horses. Oats used alone with hay may be deficient and adversely affect athletic performance.
Long yearlings and 2-year-olds require protein for maintenance and growth of muscle tissue. Exercise may increase the rate of muscle deposition, thus increasing the protein demand in young, exercising horses 10 to 20 percent above amounts required for maintenance and normal growth. Proteins are large compounds made of individual amino acids. Several of the amino acids necessary for muscle deposition cannot be synthesized by the horse’s body, and they must be supplied by the diet. As such, the balance of these amino acids or protein quality is an important consideration for exercising horse's nutrition requirements. Lysine is the amino acid thought most limiting for growth in horses.
Most commercially prepared grain mixes are formulated for exercising horses to contain between 12 and 14 percent protein with soybean meal supplementing the protein in the grain mixes. Protein deficiency in exercising horse nutrition should not be a concern if adequate amounts of grain mixes and hays are fed to meet energy needs. Protein quality rather than total protein content should be of more concern when you formulate rations for exercising horses. Low quality hays combined with grain mixes low in lysine can restrict muscle deposition in young horses, thus limiting athletic performance.
Vitamins are probably the least understood, most supplemented class of nutrition requirements in horse rations. There are two general classes of vitamins, fat soluble and water soluble. The fat soluble vitamins are stored in the horse’s body for long periods of time. Vitamins A, D, and E are the fat soluble vitamins of concern in horse rations. Exercise and growth increase the estimated nutrition requirements for most vitamins; however, increasing the vitamin concentration in rations for exercising horses may not be necessary. The increased nutrition requirements for vitamins may be more than met with the increased intake of ration in response to meeting energy needs.
The B vitamins are classified as water soluble. Thiamin and riboflavin are the two B vitamins most recommended to supplement in horse nutrition requirements. The microbes in the horse’s large intestine produce large quantities of B vitamins, and supplementation of most is considered unnecessary. Nonetheless, because of the close relationship of B vitamins with energy supplying pathways in the body, most trainers supplement B vitamins to exercising horses.
Many commercially prepared grain mixes have vitamin premixes added at levels to meet or exceed nutrition requirements for all classes of horses. If desired, an orally administered B vitamin supplement may be added to the feed. Most supplements have combinations of vitamins and minerals, so selection and use of only one supplement is desired to decrease the chance of excess feeding. Although practiced commonly, the routine use of injectable sources of vitamins has not been shown to be warranted.
The need for additional minerals in rations formulated for exercising horses is largely related to the increased mineral loss through sweat. Sweat contains appreciable amounts of sodium, potassium, chloride, calcium, and magnesium. As such, recommendations call for increases in these minerals for horses in environments or exercise conditions which promote sweating.
In general, many of the mineral nutrition requirements increase slightly with exercise. The need for additional salt (sodium chloride) is of most concern. Unlike most minerals, horses can self-regulate salt needs by access to salt blocks as long as there is free access to water. Trace mineralized salt blocks should supply most if not all the additional mineral needs for exercising horses, although some types of intense, prolonged work such as endurance riding may necessitate oral supplementation with liquid or paste electrolyte mixtures. A sample daily electrolyte mix would contain approximately 4 grams sodium chloride, 2 grams potassium chloride and 0.2 grams magnesium sulfate.
Special Concerns for Feeding Exercising Horses
How nutrition requirements are supplied to exercising horses can be more of a factor to success than what is being fed. Changes in environment, hauling and other factors which disrupt the horse’s normal schedule can cause the horse’s appetite to be depressed. As such, the potential for weight loss and poor performance is increased.
Starch Overload One area of concern when feeding large amounts of grain daily is the potential for starch overload. Large amounts of starch, or NFC, at one time overwhelm the capacity of the horse’s stomach and small intestine. The undigested starch passes into the large intestine where the normal microbial flora digest it. Large amounts of microbial digestion of starch can lead to colic and founder. As a general rule, grain mixes should be limited to levels of 0.5 percent of body weight at one feeding. Therefore, the high levels of grain inherently fed to exercising horses to meet nutrition requirements should be split into three-a-day feedings.
Timing of Feeding Another concern among trainers is the timing of feeding in relation to exercise. It is good management to allow the horse to digest its ration at least two to four hours before beginning any physical exertion. This delay would allow the majority of nutrients to pass from the stomach to the intestines of the horse. It is not recommended to restrict the horse’s ration prior to the day of exercise. Restriction of diet for longer than six to 12 hours prior to exercise may decrease the availability of energy and hence decrease athletic performance. Trainers should be careful not to make abrupt changes in the composition of the ration by restricting grain or hay or changing feeding times immediately prior to exercise. It is likely that the horse’s schedule will become disrupted on the day of performance, and the added change of diet may cause digestive tract disorders.
Body Weight Regulation Horses like other athletes are individuals and must be managed as such if maximum athletic performance is to be achieved. Horses can be expected to have an ideal performance weight, and body condition will vary slightly between individuals maintaining their ideal weight. Every trainer has a subjective ability to visually determine body weight; however, unnoticeable changes may be large enough to cause differences in performance. For that reason, some race tracks and training facilities provide scales. Comparisons of athletic performance at different body weights, weight changes before and after performance and general trends of weight changes through a conditioning program assist the trainers in regulating the nutritional and conditioning programs for each horse.
Water Although water was not previously discussed, it is a nutrient of vital concern to horses. Dehydration leads to decreased performance or more serious health problems, causing shock and death. The only time it is recommended to restrict water intake is immediately prior to exercise and during immediate recovery from exercise when heart and respiration rates are elevated. At these times small amounts of water given frequently will guard against dehydration without increasing the potential for digestive upset. Insuring adequate water intake rather than water restriction should be more of a concern, especially in hot, humid environments or prolonged bouts of exercise.
Quality of Feedstuffs Exercising horses must consume large amounts of feed per day to meet nutrition requirements. Feedstuffs must be of high quality, clean and fresh. It is not sufficient to feed large amounts of low quality or unbalanced rations in hopes that nutrition requirements will be met.
In summary, exercise can have a dramatic effect on the nutrient requirements of horses. Exercising horses can be expected to be highly individual in their needs for different nutrients and their acceptance of different rations. Exercise can place large nutrient demands on the horse, and intense management is necessary to ensure adequate intakes of balanced rations for exercising horses. Decreased athletic performance and feed related health disorders are significant problems that must be guarded against through proper ration selection and feeding management. Nutrition is but one part of athletic performance. It may be the easiest part to control; however, it will not overcome poor genetics or conditioning programs. On the other hand, it can be optimized and should not be limiting to athletic performance.
SOURCE - David Freeman
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