Equine nutrition: Health, wellbeing and performance Energy for physical performance | Protein essentials | The importance of minerals and vitamins Is your horse meeting its full potential? All horses are governed by their “genetic” potential to perform, and often as owners and trainers, there is little you can do about the breed or genetics of the horse you are working with. However, through appropriate training and adequate nutrition and care of your horse, you can ensure that he or she performs at the very best of his or her ability every time. Nutrition is the easiest thing to control. There are certain nutrients required for frequent or prolonged physical activity. These include: Water (a loss of only 15% body water is fatal) Body salt or electrolytes Energy, protein, vitamins and minerals Energy for physical performance Energy is required to fuel the body processes including muscle contraction and provide heat to maintain body temperature. The energy needs of a horse are influenced by the speed and duration of the exercise, the horse’s temperament, the weight of the rider and the horse, the type of working surface and the general metabolic efficiency of the breed or individual animal. The adequacy of the energy intake in a working horse can directly influence the horse’s performance, its vitality, and maintenance of an optimum body condition. The energy requirements of a horse increase with an increasing workload. Fig 1. Graphical description of the increased requirement for energy as the workload of horses increases If the amount of energy provided in the horse’s diet is in excess, the horse will channel the surplus energy into activity, making it “hyper-energetic”, “above itself”, “fizzy” or more difficult to handle. In a quieter horse, it will be converted into body fat. Inadequate energy in a horse’s diet will affect the animal’s ability to exercise, grow or reproduce and the horse will lose body weight as fat and protein will be utilized to maintain daily energy needs. Protein essentials Protein is the major structural component of muscles, blood and many other tissues. On a moisture and fat free basis, protein constitutes 80% of a horse’s body weight. Proteins primarily provide amino acids and nitrogen for tissue growth. A horse needs a daily intake of protein to maintain, grow and repair tissues, however, unlike energy which is stored as glycogen or fat, excess protein is not stored in the body. This means it is pointless (even in young growing horses) to feed any more protein than is recommended, it will simply add cost to your feeding program. If there is not enough protein in the diet, there will be a breakdown of protein contained in muscle and the horse will lose condition. Higher protein requirements are indicated in working horses to replace tissue degradation and losses in sweat and in lactating mares due to the protein being secreted into the milk. Excess protein in the diet is fermented in the hindgut, producing heat, which adds to the heat load of exercising horses. This basically means that excess protein isn’t good for horses that sweat as it increases the demand for water. Minerals and Vitamins Dietarily, minerals and vitamins should be regarded as a group rather than individually. As the intake of a mineral increases above that needed, the amount absorbed and/or excreted in the urine and/or faeces also increases. An excess amount absorbed may be harmful. That not absorbed may bind other minerals, decreasing their absorption and possibly resulting in a deficiency of these minerals. It is the balanced amount of all minerals in the diet that is important. Indiscriminately adding one or even several minerals to the diet is likely to be more harmful than beneficial. Therefore, minerals should not be added to the diet unless it is known which ones and how much are needed. Table 1a. Brief description of the role and importance of some of the minerals and vitamins in equine performance. Mineral Role/Importance Calcium Critically involved in bone growth, development and maintenance. Should be maintained in an appropriate balance to phosphorus. Deficiencies result in bone deformities/skeletal weakness, joint problems, may lead to muscle weakness and conditions such as “tying up”, and the “thumps” in heavily sweating, exhausted horses. Phosphorus A deficiency in phosphorus can result in retarded bone formation, retarded growth, poor appetite, infertility and poor conception and lowered milk production. Sodium Essential for normal growth. Key electrolyte in all performance animals. Critically involved in normal nerve and muscle function, and carbohydrate digestion. Sodium is often inadequate in diets. Magnesium Important electrolyte in muscle contraction, body fluids and metabolic enzymes. Potassium Involved in nerve and muscular function. Deficiencies can result in a reduced appetite, retarded growth, weight loss, and dehydration. Sulfur Essential for healthy hair, skin and hooves. Involved in oxygenation of the brain to maintain oxygen balance and works closely with B vitamins for many basic metabolic functions. Is part of many essential amino acids. Iodine Incorporated into the hormone thyroxin in the thyroid gland with regulate the metabolic rate. Deficiency can reduce metabolic rate and exercise tolerance. In recent years, iodine toxicosis in horses has been much more frequently reported than iodine deficiency. Iodine toxicosis may occur as a result of feeding seaweed (kelp). Seaweed may contain as much as 1850mg/kg of iodine, at which level more than 20g of it per horse per day would be harmful. Zinc Essential in bone, cartilage and hoof formation. Deficiency can result in reduced appetite, retarded growth, dry thickened skin and hair loss in severe deficiencies. Copper Required for the development of bone, joint cartilage, elastic connective tissue, uptake and utilization of iron and copper containing metabolic and tissue anti-inflammatory enzymes. Deficiency can result in lameness in growing horses and anaemia. Manganese Contributes to carbohydrate and fat metabolism and formation of chondroitin sulfate in cartilage of joints. Cobalt Integral in synthesis of the Vitamin B12 and is involved in the formation of the oxygen carrying component of red blood cells. A deficiency can result in anaemia. Selenium Deficiency can result in poor muscle development and pale, weak muscles (White muscle disease) in foals on deficient diets. Can also result in poor performance in racing horses, and may predispose to “tying-up”, lower fertility in mares. Table 1b. Brief description of the roles and importance of some of the vitamins in equine performance. Vitamin Role/Importance Vitamin A (ß-carotene Retinol) Fat soluble natural vitamin essential for growth processes. It is required for visual pigments in eyes, bone remodeling, tendon strength, health of skin and mucus membranes. Deficiency results in progressively poor night vision, loss of appetite, poor growth, infertility in mares (older mares more affected), reduced tendon strength, and a higher risk of respiratory infections. Vitamin D (Ergocalciferol Cholecalciferol) Critically concerned with the absorption, regulation, metabolism and excretion of calcium and phosphorus. Deficiency depresses calcium uptake and can lead to abnormal gait, lameness, weak bones and swollen joints. Vitamin E (α-Tocopherol) Essential fat-soluble vitamin and has an antioxidant activity to protect against oxidation of compounds in food, and within fats in membranes of muscles and body tissue. Has an antioxidant function and supplementation has been shown to improve track performance in racehorses. It is recognized as a compound which dilates capillaries and preserves capillary walls. It is also known to increase cardiac efficiency significantly, and reduce lactic acid production. B Group Vitamins B Group vitamins play a role in the release of energy, and are needed for numerous essential body functions. Symptoms of deficiencies of B Group vitamins include loss of appetite, abnormal heart beat, muscle tremors, in coordination, stiffness in limbs and lung fluid build-up. In diets consisting largely of cereal grains, protein meals, chaff and dried hays, natural forms of B Group vitamins are generally in short supply. Injections do not elevate blood levels for very long and supplementation is best given in the feed. Summary Inadequate energy, protein, vitamin and mineral levels are best diagnosed and corrected by evaluation of rations. This involves weighing out each of the ingredients in a ration and evaluation of the nutrient levels in the ration as a whole to the recommended nutrient levels of the particular horse at its particular level of activity. Please refer to our support page for further information.