Protein features frequently in discussions on feeding, nutrition and performance. Alternately feared and revered, it is part of the bigger picture of conditioning/nutritional protocols that result in specific changes in body composition and performance.
The word protein comes from the Greek word ‘protos’, meaning ‘first’, because protein is the primary basic constituent of all living cells. It makes up 3/4 of the dry weight of most living cells and is involved in the formation of hormones, enzymes, antibodies and many other functions essential to life.Protein is a collection of amino acids tied together. Once the protein is consumed and digested the amino acid chains breakdown into single amino acids. To appreciate how much the racehorse depends on receiving the correct amino acids in the diet, is to be aware of how dynamic the equine system is. Every second the bone marrow makes millions of red blood cells; every four days the blood platelets and most of the lining of the gastrointestinal tract are replaced; every 10 days, most of the white blood cells are replaced and the number of muscle cells repaired or created in horses that are training and racing is huge. In addition, necessary for muscle growth and repair, strong tendons, optimal energy metabolism, increasing bone density, joint health, hoof wall thickness and greater overall soundness is the interaction of vitamins and minerals with amino acids.The horse requires a precise number and balance of amino acids. Essential amino acids cannot be synthesized by the horses system and are so-called, because it is essential that they receive them every day in the feed. The exclusion or a deficiency of even one essential amino acid from the diet will reduce total body protein synthesis. In horses where everyday maintenance is necessary and improvement with training is required, the creation of new cells is a priority. If just one amino acid in the profile is missing the creation of new cells stops.
Horses receive amino acids from the protein in both concentrates and hay. Every protein source has a different combination of amino acids. Some combinations are very good and some not so good. For this reason, the total protein of horse feed is a worthless term, unless you know the amino acid profile. For example, the feed tag might say 14% crude protein, but to the horse, if all the amino acids are not supplied, it may be only 8 or 9% usable protein. The more unusable protein the horse consumes the more he has to excrete. The feeding of unusable protein stresses the horse’s system. Excess protein can contribute to higher heart and respiratory rates, increased sweating and dehydration.
While some studies have concluded that the racing standardbred does not need additional protein, they do not take into account the quality of the protein. Poor quality protein in terms of amino acid profile, can contribute to the gradual weakening of supportive tissues, bone loss, muscle atrophy and the weakening of blood vessel walls that eventually lead to bleeding or breakdown. What is important is that the horse receives the amino acids that it needs in the correct amounts, readily digested and absorbed.
Over the centuries, horsemen and women have ground, cracked, crushed, boiled, dry-extruded and pelleted feeds for horses. They have done this to increase the digestibility of the feed and to decrease the risk of grain overload, a major player in colic, diarrhoea and laminitis. However, all amino acids have a different melting point and many of these older methods of grain processing result in damage to the amino acids and little improvement in digestibility. Soybeans and processed grain by products must go through some sort of heat process. This heat can destroy the most important essential amino acids. Feeds such as brewers grain are almost always heated at a very high temperature. This heat process destroys many valuable amino acids and makes the feed unbalanced, preventing the horse from getting the full value of the feed protein and taxing the liver and kidneys in excreting all the out of balance and, therefore, unusable amino acids.
The most recent advance in preparing feeds for horses is steam-extrusion. Whereas essential amino acid losses of up to 50% have been measured during dry-extrusion, losses during steam-extrusion are less than 5% and digestibility of the feed increases to over 90%. The application of steam-extrusion and the provision of high levels of essential amino acids in the correct balance are fundamental. Protein in general should never be fed in excess to any horse and neither should there be an overload of protein types that are poorly digested or that the horse cannot use. Essential amino acid deficiencies can occur even if diets containing excess protein and deficiencies cannot be corrected by feeding more of it, if it is not correctly profiled.
The second, separate issue is restoring protein balance after hard work or racing and encouraging the building of lean muscle mass. During hard training and racing, standardbreds damage muscle tissue as a result of the production of high levels of lactic acid and exertion. Muscle must be repaired rapidly to maintain improvement, prepare for the next training session and minimise delayed muscle soreness and stiffness. While in training or before and after racing, dietary programs must be chosen with care to facilitate quick recovery. Hard work causes a decrease in protein production that continues for a few hours after exercise has ceased. Protein in muscle is extensively broken down during exercise and this process serves a number of functions, but it is during recovery that the protein will be working hardest, repairing and building the rips and tears that occur during training.
No matter how balanced the diet is beforehand, exercise naturally causes a disruption. During exercise muscles use fuel at a very high rate and this is a catabolic process, i.e. it involves the breakdown and utilization of body reserves. However, we are able to switch the catabolic environment into an anabolic (ie, a building of body tissues and reserves) environment after work by supplying the proper tools. Feeds chosen must contain protein that is profiled properly for amino acids, along with minerals, vitamins, fat and carbohydrates.
Nutrition is a powerful tool when used properly. To the extent that we focus on the challenging bigger picture of conditioning/nutritional support protocol, the horse can harmonise the multiple systems necessary to reach genetic potential. High quality protein in terms of amino acid profile and availability is essential for maximum performance of the Standardbred racehorse.