Part 1- Nutrition
Part 2- Conditioning and fitness
Part 3- Environmental Factors
Part 4- Podiatry
Part 5- Complementary Medicine
Part 1 Nutrition
Clair Thunes, PhD, teaches equine nutrition and equine exercise physiology in the UC Davis Department of Animal Science and has competed in a number of sport disciplines including eventing, show jumping, and dressage. She is also an independent equine nutritionist and owner of Summit Equine Nutrition, LLC. She offers the following perspective on optimizing nutrition for equine athletes.
Today's performance horses lead lives that are very different from their wild ancestors. Yet physiologically, they are not so different: modern horses still have a digestive tract where more than 50% of its volume is given over to the fermentation of forages and that still secretes acid and bile 24 hours a day because it expects almost continuous grazing rather than infrequent meals.
An equine diet should have a foundation in forage, regardless of whether the horse is a retired pasture ornament or an Olympic-level show jumper.
Photo: Photos.com
Horses evolved eating grasses that for the most part were high in complex carbohydrates, requiring fermentation by hindgut bacteria. The relationship between these bacteria and the horse is mutually beneficial because the horse absorbs the byproducts of the fermentation processes as an energy source. Therefore, maintaining the health of the microbial population is a vital component of nutritional management. The bacterial population requires that adequate amounts of complex carbohydrates be provided in the diet and that the diet stay relatively static with only gradual changes.
An appropriate feeding program for any horse takes into consideration the horse's digestive anatomy and physiology. Ideally, the primary diet should have a foundation in forage, regardless of whether the horse is a retired pasture ornament or an Olympic-level show jumper. Performance horses might need more calories in their diet than can be met from forage alone; as a result, the temptation is to feed increasingly high levels of calorie-dense feeds. The focus of the ration can easily become these supplemental energy sources, with less and less attention paid to the ration's forage components.
Because many supplemental feeds fed to performance horses are fortified, this can create a perception that the forage is nothing but filler. However, the majority of horses should be consuming a minimum of 1.5% of their body weight per day as forage, or approximately 18 pounds a day for a horse weighing 1,250 pounds. Thus, in most cases the forage portion of the diet provides the majority of the calories, protein, and minerals (such as calcium and phosphorous), making it far more than just filler.
Careful selection of forages can mitigate a number of problems observed in equine athletes. For most performance horses, this forage will be hay. Undesirable hay bellies, which are caused by consuming large amounts of indigestible, poor-quality forage, are best fixed not by reducing the amount of hay fed but rather by switching to a hay that is more easily digestible. Conversely, feeding a lower-quality hay to horses that typically need calorie intakes restricted will allow a greater amount of hay to be consumed without the risk of weight gain. With careful hay selection, the amount of hay fed can be maximized for each horse, thus honoring the digestive physiology and reducing the risk of conditions such as equine gastric ulcer syndrome and stable vices like wood chewing.
The purpose of concentrate feeds and supplements should be to provide what is missing in the forage portion of the ration. For nearly all forages, this means a source of trace minerals, certain vitamins and fatty acids. For many horses competing at the entry levels of their disciplines, feeding a nutrient-dense, low-calorie ration balancer with a small serving size in combination with hay will provide nearly all of the necessary additional nutrients.
For horses unable to maintain condition on forage and a ration balancer, a more calorie-dense feed should be added to the ration. There is a tendency within certain disciplines for horses to be maintained with too much condition, which results from overfeeding. There are two major consequences of these practices:
- Extra condition adds unnecessary wear and tear on joints and soft tissues and can result in soundness issues; and
- Extra condition could produce negative behaviors.
Horses that are overfed calories can become exuberant, and when this is not given an appropriate outlet (such as turnout), undesirable behaviors under saddle can result. This is particularly troublesome in the show arena and can lead to the pursuit of calming supplements and other measures to create a more tractable mount. In most cases, the simplest and most appropriate solution would be to feed a more appropriate diet.
For those struggling to keep weight off their easy keepers, or those who feed commercial feeds in quantities less than the manufacturer-recommended amounts, a suboptimal diet can result. Horses might appear to be in good condition when, in fact, they are suffering from a level of malnourishment. For example, manganese is needed for the creation of chondroitin sulfate and copper for the formation of collagen, the foundation of tendons and ligaments. Without careful attention to the diet, these deficiencies can potentially go unnoticed. The long-term impact of suboptimal diets is not well-documented in horses; however, the harder a horse works and the greater demands made on metabolism and physiology, the more likely nutrient deficiencies will negatively impact both health and performance.
Fat sources have become a common ingredient in many performance horse feeds. Because fats are very energy-dense (2.25 times more calories than an equal weight of carbohydrate), they are an effective way of adding large amounts of supplemental energy to a ration. Fat also does not raise blood glucose and insulin the way high-starch intakes do, which is an important consideration when dealing with horses that are sensitive to nonstructural carbohydrates, such as those with polysaccharide storage myopathy or insulin resistance.
Fat is susceptible to rancidity and when a high-fat diet is fed to a horse, the horse is at a higher risk of developing cellular oxidative damage. Feeding vitamin E, a natural antioxidant, alongside a fat (usually at 1,000-2,000 IU per half-cup of oil) can help offset that oxidative damage. Additionally, high-fat feeds that have been stored in hot environments or that are not fresh could have higher levels of rancidity, so ensuring that the feeds purchased are fresh is important.
There is also much anecdotal evidence that horses fed fat instead of grains are less excitable. Research has shown that there might in fact be merit to these claims, with dressage horses fed high-fat diets being less easy to startle and having lower resting cortisol (a measure of stress) than when fed a diet higher in starch. Other research has confirmed that foals fed high fat and fiber diets cantered less often and for less time than those fed calories from starch and sugar. More is not always better though. When fed in excess, fat has the potential to disrupt hindgut fermentation and absorption of some minerals and vitamins. As always, the key is in finding the correct balance.
Performance horse managers are constantly on the lookout for inflammation, especially of the joints, but they also have to battle other inflammatory conditions such as hives and laminitis. As all of these conditions can keep a horse out of the competitive arena, there is a lot of interest in nutritional aids in the form of nutrients with potentially anti-inflammatory properties such as various joint supplements, omega-3 fatty acids, and, most recently, resveratrol and turmeric. However, potentially anti-inflammatory supplements could violate anti-doping regulations.
Flax provides a good source of omega-3 fatty acids at approximately four times more omega-3 than omega-6.
Photo: The Horse Staff
Unlike plants, horses and other mammals are unable to create omega-3 and omega-6 fatty acids, so these nutrients must be provided in the diet. Good-quality fresh pasture provides approximately three times more omega-3 fatty acid than omega-6. The amount of omega fatty acids is lower in hay as they are not heat stable. Flax provides a good source of omega-3 fatty acids at approximately four times more omega-3 than omega-6. Flax can be fed whole or is available for purchase in ground, stabilized forms. Unless stabilized, the fatty acids will oxidize once ground. Grains and oils tend to provide larger amounts of omega-6 than omega-3. Corn oil, for example, provides approximately 45 times more omega-6 than omega-3 fatty acid.
The relative amount of omega-3 to omega-6 in the diet could have important implications for inflammation within the body. The ratio in good quality grass pasture is about 3:1 omega-3 to omega-6. High-grain diets will throw the ratio the other way, and this has the potential to be pro-inflammatory versus anti-inflammatory. Research conducted at UC Davis revealed a 60% drop in biomarkers of inflammation after supplementation with a product containing an omega-3 to omega-6 ratio of 4:1. Competition exists between omega-6 and -3 fatty acids at the cellular level; therefore, the dietary fatty acid composition has the potential to impact a number of important cellular level functions relevant to performance.
Approximately 15 to 25 g per day of supplemental omega-3 fatty acid is often recommended for a 1,100-pound horse; a cup of ground flax provides about 22.5 g. The National Research Council (NRC) requirement for omega-6 is 0.5% of dry matter intake, or about 5.5 g per day for a 1,200-pound horse eating 2% of body weight in feed.
Vitamin E is a powerful antioxidant that protects sensitive cell membrane components from oxidative damage. Currently, the NRC recommends a minimum daily intake of 1.6 to 2 IU/kg body weight per day for working horses, or about 1,000 IU per day for a 1,200-pound horse. There is research showing that levels above this could improve performance in some horses, especially those doing rigorous speed or endurance work or suffering from neuromuscular disorders. Horses who fail to develop an adequate topline despite normal development and soundness might also benefit from additional vitamin E supplementation.
Common over-the-counter vitamin E supplements will often contain selenium. The margin of safety for selenium is far below that of vitamin E, so it is important that vitamin E is supplemented alone unless a selenium deficiency is detected. Consult with your veterinarian before initiating a combination supplement.
A diet of good-quality fresh pasture provides significantly more vitamin E than the above recommendation. However, due to oxidation processes, naturally occurring vitamin E in pasture declines dramatically during curing for hay as well as in other feed ingredients that undergo processing. Losses in hay can be so great that stored forage should not be relied upon as an adequate source for performance horses. While better-quality commercial feeds provide a source of vitamin E, in some instances separate vitamin E supplementation may be justified, especially for horses in intense work and those showing signs of muscle soreness or prone to recurrent tying-up.
For maximum absorption, vitamin E should be supplemented in the natural ?-tocopherol form. Water-soluble versions exist, which are the most absorbable and are recommended for horses with neuromuscular conditions.
Vitamin E appears to play a role in a number of neuromuscular diseases including equine degenerative myeloencephalophathy, equine motor neuron disease, and muscle atrophy conditions. Further work is needed to better understand its role in these conditions.
So where does all of the above information leave us as far as making sound nutritional decisions for our horses? A good initial rule of thumb is to always remember how the horse's digestive anatomy and physiology work and to design a feeding program that honors this. This means starting with forage and selecting the right forage for the individual horse. All hay must be clean and free of weeds, molds, and dust. Select the hay that allows you to feed the greatest amount possible while still maintaining a desirable body condition. Keep in mind that access to fresh green pasture is not ideal for all horses. Consult with your veterinarian regarding individual restrictions.
Hay should be tested whenever possible, especially when several months' worth are purchased at one time. Compared with the cost of hay, testing is a very modest investment starting at around $30 for information about the calorie, protein, carbohydrate fractions, macro- and trace mineral content. Make sure that the lab chosen to run the analysis provides equine-based information. When an analysis is not viable, a thorough visual assessment can give some nutritional information. Hay with a greater proportion of leaves relative to stems is higher quality and will have a higher calorie and protein content versus a stemmy hay with lower leaf content.
Alfalfa is a higher-calorie hay than grass hay, making it less desirable for easy keepers but a good choice for harder keepers. It can be included up to about 30% of the total forage. Above that amount, protein and calcium intakes become excessive.
Once the hay is selected, nutrients not present in hay in adequate amounts need to be provided by some additional means. If the horse is able to maintain condition solely on hay, then a broad-spectrum supplement providing approximately 50 mg of copper and 200 mg of zinc (this is half of the NRC requirement for a 1,100-pound horse at rest) or a ration-balancing feed (look for feeds with a 1- to 2-pound serving size per 1,000 pounds of body weight) should to be added to provide necessary trace minerals. The benefit of the ration-balancing feed is that it will also provide a source of quality protein that could be lacking in some grass hays. For some very easy keepers, even the limited calories provided by a ration balancer might be too many, making a supplement a better option.
For horses needing additional calories to maintain condition, a performance or senior feed will be a better option. It is very important to pay attention to the feeding directions and select a feed that you can feed at the recommended amount. This is particularly important for senior feeds that are "complete" feeds, meaning that they provide all of the necessary forage as well and therefore have very large serving sizes, upwards of 15 pounds per day in some cases. Read the labels to determine the serving size for your horse's needs and purchase accordingly. Also look at the label to determine whether the feed is providing calories from fat (% crude fat) or starch. Feeds with a low percentage of crude fiber tend to have a higher starch content. Look at the ingredient list to see whether the feed includes beet pulp, soy or almond hulls—desirable sources of fermentable fiber—and do not shy away from wheat middlings and wheat mill run, which provide the same calorie content as many grains but with half the starch.
Beyond this, be sure to provide a source of salt and consider adding supplemental sources of omega-3 and vitamin E. Many horses do not consume enough salt from a block to meet their minimum sodium requirement, which is equivalent to a 2-pound block of salt a month for a horse weighing 1,100 pounds living in cool weather and doing no work. Therefore, it is advisable to add 2 tablespoons (1 ounce) of white salt to the daily feed in addition to having access to a block. An additional electrolyte might be needed during hard work and/or hot weather.
Elite human athletes have come to realize that, while they might think they know how to eat properly for their chosen sport, there are real benefits to working with a nutrition professional with the expertise to fine-tune their diet for maximum performance ability. This is where working with an independent equine nutritionist can really make a difference. They can create a diet based on the forage and help with correct product selection, thus ensuring that your horse is getting everything needed while at the same time honoring digestive anatomy and physiology.
Given the large amount of money spent on feeds and supplements every month, consulting with an independent equine nutrition professional is a sound investment, with most offering a range of services priced from about $100 for an hour-long phone consultation, to $200-$300 for an in-depth ration analysis. A good independent equine nutritionist will be basing their recommendations on the available science, not the need to sell certain products.
There is still much work to be done when it comes to research in sport horse nutrition:
- Studying the effectiveness of potentially anti-inflammatory nutrients in horses such as quercitin, resveratrol, and turmeric.
- Quantifying whether mimicking natural eating habits in stabled horses lowers stress.
- Making a commitment to support general sport horse nutrition research.
Advancing our knowledge in these areas will help provide nutritionists and veterinarians with the tools they need to make sound feeding recommendations and to improve both the welfare and performance of sport horses.
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Stacey
Hartpury Saddlery Shop
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Reprinted from The Horse Report (Spring 2014) with permission from the Center for Equine Health, School of Veterinary Medicine, University of California, Davis (UC Davis).
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