Am I feeding the right type of concentrate for my horses’ lifestage and lifestyle?
Horses in different stages of life and with different levels of activity will have different nutrient and caloric requirements. Choosing a feed to fit your horses’ lifestage and lifestyle will help to ensure that those requirements are being met.
Source: Purina Mills Equine Specialist
Is the forage high quality and available in sufficient quantities?
It is not uncommon to find that hay and pasture that appear to be of good quality are actually poorly digestible or low in certain nutrients. By having your hay and pasture grass tested you can assess the nutrient content and digestibility of your forage source. Additionally, most people feed hay by the flake and do not weigh it. There is a lot of variability in the weight of a flake of hay that can be dependent on hay type and the way it was baled. Weighing hay is a good way of determining that you are feeding enough. While it is not possible to weigh the grass your horse is taking in while grazing, careful inspection of pastures to ensure that there is an adequate quantity of edible grass present is a good idea.
Source: Purina Mills Equine Specialist
Is my horse properly taking in, chewing and swallowing both forage and feed?
By observing your horse while eating hay, grass and feed, you may find that while he is taking in food he may not be actually chewing and/or swallowing it – this is especially common in older horses with poor dentition that may be quidding forages or dropping feed. The horse appears to be eating well, but in actuality the forage or feed is actually balling up in the cheeks and then being spit out by the horse.
Source: Purina Mills Equine Specialist
Have you ever watched a pendulum swing? It swings way to the right, and then goes back to center. Then it swings way to the left, then returns to center again. In human nutrition, the sugar and starch pendulum appears to be returning to center. In equine nutrition, however, that sugar and starch pendulum seems to be hung up way off to the side.
Before we talk about the “evil” nature of sugars and starches (and therefore grains since they usually provide the majority of starches in a horse’s diet), we need to talk about carbohydrates. Sugars and starches are carbohydrates, but fibers are also carbohydrates. Fiber carbohydrates (structural carbohydrates) are important in a horse’s diet, and are primarily provided by the forages (grass or hay) that the horse eats. When people talk about feeding a “low carb” or “no carb” diet to horses, that implies that we need to reduce or eliminate the hay
or grass in the horse’s diet as well as the concentrate (or grain-based) feeds. That is usually not what we want to do, because fiber is essential to maintain the health of the horse’s digestive tract. The sugars and starches are nonstructural carbohydrates or NSC (sometimes referred to as soluble carbohydrates). In some situations it may be beneficial to reduce the NSC in a horse’s diet.
Are nonstructural carbohydrates “evil”? In the horse’s small intestine, most nonstructural carbs are broken down into glucose, a simple sugar. The glucose is then absorbed into the blood stream, and is carried to various tissues where it is used as fuel, or stored as glycogen (in the muscle or liver, where it later used as fuel) or as fat. Glucose is very important for the horse to function properly, as it is the only fuel that can be used by the brain, it is used to a large extent by the hooves, and it is the only substance that can be used for making glycogen. Studies have shown that horses that use up all their glycogen and are not provided glucose to replenish the glycogen stores show greatly reduced performance capabilities. So glucose is vital to the health and well-being of the horse. Again, glucose comes primarily from NSC.
So, again, are nonstructural carbohydrates “evil”? We know that too much NSC (particularly starch) in a horse’s meal can cause problems. We want the NSC to be digested in the small intestine, but if we feed a large meal that contains so much starch that it overflows from the small intestine into the large intestine, it may cause digestive disturbances such as colic or laminitis. Studies have shown that feeding no more than about 0.5% of a horse’s bodyweight of grain in one meal will reduce the risk of grain overload into the horse’s hindgut, therefore reducing the risk of colic or laminitis.
For laminitic horses (horses that have been previously been diagnosed with laminitis) feeding less NSC may be helpful in reducing the chance of a recurrence. Horses with chronic laminitis may be more susceptible and more sensitive to NSC in the diet.
There are some horses that suffer from disorders such as Cushing’s Syndrome. This disorder may cause a problem in the regulation and use of glucose in the body. The hormone insulin helps regulate glucose, by causing it to be removed from the blood into the tissues where it is used or stored. In horses that suffer from Cushing’s Syndrome, the insulin may not function properly to regulate the glucose, and we see high levels of glucose in the blood. We call these horses “insulin resistant”. In these situations, it may be beneficial to feed less NSC so that there will be less glucose provided by the diet.
Another situation in which low NSC diets are recommended is for horses diagnosed with “Equine Metabolic Syndrome”. These horses are usually obese, and blood tests show them to be apparently “insulin resistant”. However, in many cases if the horses are put on low calorie diets and lose weight, their glucose and insulin values return to normal.
Once again, are nonstructural carbohydrates “evil”? In my opinion, the answer is a firm “NO”. There are some situations in which some horses may benefit from lower levels of NSC in their diets. However, we need much more research to determine where the level of NSC needs to be, because the horse still needs glucose for brain, muscle and hoof function. We don’t know at this point where the lower limit of NSC in the diet is to ensure adequate glucose to supply the body’s needs. We also do not know where the upper limit is to reduce the potential for NSC in the diet to cause problems for insulin resistant horses. As an equine nutritionist, I try to ensure that the total diet includes
all the essential nutrients to meet the horse’s nutritional needs without exacerbating any medical conditions. For most typical horses, the amount of NSC in a standard diet of grass or hay and concentrate feed will cause no problems. In situations where the NSC may be an issue, there are factors to consider other than just how much grain is in the horse’s diet.
Horse owners almost always look at the grain portion of their horse’s diet to reduce the NSC. However, just because a feed contains grains, it does not mean that the feed is high in NSC. Conversely, just because a feed does not contain whole grains does not mean that it is low in NSC. Different ingredients in a feed contain different amounts of nonstructural carbohydrates, and it is the total mixture of ingredients that determines the NSC content of that feed. Purina Mills has several feeds available that are low in NSC. And more importantly, those feeds are formulated to contain all the nutrients necessary to meet the horse’s nutritional needs.
Further, we need to keep in mind that fresh grasses and some hays can contain fairly substantial amounts of NSC. When dealing with a horse that is suffering from a disorder that may be aggravated by high levels of NSC, it is vital to look at the forage portion of the ration as well as the concentrate to determine the best total diet for that horse.
Finally, it is essential to keep in mind that each horse is an individual with individual needs. When we start looking at individuals with special needs such as those with Cushing’s Syndrome, or obese horses, or laminitic horses, there is no cookie cutter approach to meeting the horse’s nutritional needs as well as the medical needs.
At Purina Mills, we have a large variety of feeds available to meet the needs of horses in many different situations. We have a number of equine nutritionists and veterinarians involved in current research to determine the best blends of all ingredients and nutrients to provide the safest and most effective ways to feed horses. Our goal is to provide the best nutrition for your horse by supplying the nutrients necessary to support your horse’s health, performance, and longevity.
Katie Young, Ph.D., Consulting Equine Nutritionist
When choosing a horse feed, looking at the guaranteed analysis can help you determine if the nutritional content of that feed is appropriate for the age and activity level of your horse. You’d think that two products that both contain 14% protein, 6% fat, etc. would be pretty much the same feed. However, products with similar guaranteed analyses may be manufactured using different formulation strategies and have very different formulas. This can affect the nutritional value for your horse. The most common formulation strategies are “Least-cost” formulas and “Fixed” or “Locked” formulas. Both strategies have benefits and drawbacks. There is a formulation strategy that Purina uses for premium horse feeds, “Constant Nutrition” formulation, which is more nutritionally accurate than either of the other strategies.
Least-cost formulation allows a manufacturer to adjust the ingredients in the formula based on cost. As long as the formula still meets the guaranteed analysis, the manufacturer can change the ingredients used in the formula. In some circumstances, the change in ingredients doesn’t change the effectiveness of the diet so it makes sense to meet the nutritional needs of the animal in the least expensive way. There would be no benefit to making a more expensive ration to achieve the same results. For instance, if you are feeding cattle and being paid for weight gain and a least-cost formula will not change the rate of gain or feed efficiency of the cattle, but will be less expensive to feed, that just makes good business sense. However, in some cases, especially when feeding horses, a major change in ingredients can dramatically alter the effectiveness of the diet, even when the nutrient levels don’t change. A good example of this would be substituting cottonseed meal for soybean meal in a diet for growing horses. Soybean meal and cottonseed meal may both have similar total protein content and could be interchangeable in a formula to meet the protein guarantee. However, cottonseed meal does not provide the same quality of protein to support growth as soybean meal, and young horses will not grow as well eating a feed with cottonseed meal as the protein source. So, in this case, the least-cost formula may be less expensive per ton but the loss in animal performance will negate any cost savings. In addition to potential for reduced performance, there is always the potential for reduced palatability or digestive upset in horses when large shifts in ingredients occur in their feed.
With fixed or locked formulas, the same ingredients and amounts of ingredients are used every time the feed is made, regardless of price or nutritional variation of those ingredients. This sounds like the most consistent way to make horse feed; however, there is a significant drawback. All ingredients, even high quality ingredients, have variation in nutritional content. For instance, all oats will not have the same protein or mineral content. If the formula is completely locked and not taking into account the nutritional content of the individual ingredients, the level of nutrition provided in the finished product will vary. Horses do benefit from consistency in their diets, but they don’t have specific requirements for certain ingredients. The purpose of ingredients is to provide nutrients the horse needs. So, while a fixed formula does provide the same amount of ingredient in every bag, it may not provide the same level of nutrition. For example, a horse feed made of 49% oats, 20% beet pulp, 16% corn, 8% alfalfa and 7% soybean meal would average 14% protein, using the average book values for these ingredients. However, with the typical range in protein content of these ingredients, the end product could range from 12.4% to 21.1% protein. Other nutrient levels will vary as well. So, while a fixed formula does insure a consistent ingredient profile, it won’t provide the most consistent level of nutrition for the horse.
“Constant Nutrition” formulation is a key component of the Purina FeedGuard™ Nutrition System. This strategy provides consistent, reliable nutrition in every bag of premium Purina horse feed. Under the Purina FeedGuard™ Nutrition System, stringent quality standards are set for ingredients which are purchased only from an approved list of suppliers that meet those strict criteria. Then, when ingredients arrive at a manufacturing facility, the ingredients are inspected, sampled and analyzed for nutrient levels. This is more accurate than using published book values or supplier averages for nutrient levels of ingredients. If an ingredient is approved, then the tested nutritional content is entered into the formulation system, which then makes small adjustments in amounts of ingredients to maintain consistent nutrient concentrations in the finished product. There are strict restrictions for how much adjustment is allowed to ensure consistency in formulation. For example, the amount of soybean meal may be adjusted slightly to compensate for lower protein in another ingredient, but cottonseed meal could not be substituted for soybean meal. This formulation strategy ensures that horses always receive the most consistent nutrition possible, and that horse owners always get exactly what they pay for.
Karen E. Davison, Ph.D.
Manager- Equine Technical Services
Land O’Lakes Purina Feed
Water is the main component of the body. In fact, an average 1000 pound horse is roughly 660 pounds (80 gallons) of water. About two-thirds of this water is inside cells, called intracellular fluid, and one-third is outside cells or extracellular fluid. To function normally, the body must keep the amount of water in these areas in balance and relatively constant. This is termed water balance. The water in the body contains dissolved mineral salts called electrolytes, primarily sodium, chloride, potassium, calcium and magnesium. These dissolved electrolytes exist as ions, which are charged particles that conduct electric currents, thus the name electrolytes. Electrolytes are used to maintain voltages across cell membranes, and are distributed through the body in a highly ordered way. Any disruption of this order can result in severe body dysfunction, including heart and gastrointestinal problems, muscle cramps and impaired brain and nerve function. Sodium and chloride concentrations are normally higher in extracellular fluid, while potassium concentration is higher in intracellular fluid. Electrolyte balance is tied very closely with water balance.
Water and electrolytes are excreted from the body primarily through sweat, urine and fecal output. The body attempts to maintain a balance between dietary intake of electrolytes and excretion rates. Kidneys adjust the volume and concentration of urine based on the water and electrolyte balance in the body through an intricate hormone signaling system. Electrolytes are not stored in the body, so the amount needed daily must be provided in the diet. If dietary electrolyte level is lower than needed, the kidneys will conserve and reabsorb electrolytes. If dietary electrolyte supply is more than needed, the kidneys will flush any excess. This very complex mechanism keeps water and electrolyte balance tightly regulated under normal circumstances. However, when the relationship between intake and output is challenged, normal mechanisms may not maintain the balance.
Hard work, especially in hot and humid conditions will challenge normal water and electrolyte balance mechanisms. Under these conditions, horses can lose as much as four gallons of sweat per hour, which carries with it approximately 10 tablespoons of electrolytes – primarily sodium, chloride and potassium. Human sweat is hypotonic, meaning the concentration of electrolytes in the sweat is lower than the concentration in the blood. As people sweat, sodium concentration in the blood rises. This triggers the thirst response causing the person to want something to drink. Horse sweat is hypertonic, the concentration of electrolytes in the sweat is higher than the concentration in the blood. As the horse sweats, sodium concentration in the blood remains unchanged even though large amounts of sodium are being lost in the sweat. Without the rise in blood concentration of sodium, the thirst response doesn’t kick in. This is why dehydrated horses often show no interest in drinking, which simply makes the situation worse.
Hay and pasture contain high levels of potassium and a normal diet will provide adequate potassium to meet requirements of most horses. Usually, only hard working horses that sweat for prolonged periods need additional potassium supplementation. Most commercial horse feeds contain 0.5 – 1.0% added salt (sodium chloride) which, along with free-choice access to a salt block, will supply adequate sodium and chloride to meet requirements of horses in light activity. Horses being ridden regularly and sweating moderately on a daily basis cannot eat enough salt from a salt block to meet their needs. Providing 2 – 4 tablespoons of loose salt daily in the feed will meet the increased requirements. For horses that are sweating profusely, a mixture of 2/3 sodium chloride and 1/3 potassium chloride (Lite salt), would provide adequate sodium, chloride and potassium to replenish the higher losses. Commercial electrolyte supplements are also available, but should contain sodium chloride as the primary ingredient.
Providing daily electrolyte supplementation beyond what a horse needs to maintain balance can be very counterproductive. The kidneys will become very efficient at flushing the excess electrolytes out of the system and then on a day the horse really needs a higher level, they won’t be available. The current recommendation for electrolyte supplementation is to provide additional electrolytes the day before, the day of and the day after a horse is going to work very hard and sweat a great deal. It is also very important that electrolytes are only given to well hydrated horses. Since you can lead a horse to water but you can’t make him drink, dehydrated horses should receive fluids intravenously to be sure water balance is adequately restored.
By Karen E. Davison, Ph.D., Manager – Technical Services, Purina Mills, LLC
a manufactured pelleted ration for horses, made of grains and other plant products with vitamins and minerals added (Photo credit: Wikipedia)
By Tina M. Anderson, PhD
A horse in its teens may typically be thought of as “old”, but the reality is that the genetics of the individual, plus how it was cared for during its life, will dictate when the nutritional needs begin to shift from that of an adult mature horse to that of a geriatric horse. That point in life varies among horses and is a gradual process that doesn’t happen overnight.
It is estimated that there are over 700,000 senior horses living in the United States today. There was a “horse baby boom” in the mid-to-late 1970s, making 9-11% of the total horse population today older horses. Many of these horses are well into their 20s or 30s, and still live very healthy, active lives due to better care and feeding.
The best manner in which to care for older horses is to address their special needs prior to any significant decline in condition or health. As always, your veterinarian plays a key role in helping to ensure the continuing good health and longevity of your horse. Three main areas of attention needed for the older horse are nutrition, management, and health.
Dental – Teeth that are worn or missing make chewing difficult for the horse. Poor dental care can also cause mouth ulcers resulting in pain. Poor teeth contribute to the horse not chewing its food long enough to produce the amount of saliva necessary for proper digestion. Saliva not only contains enzymes important for the digestion of feed, but it also helps to lubricate the esophagus for ease of swallowing. If a horse is dropping bits of feed or forage out of its mouth, chances are there is an underlying condition in the mouth. In addition, feeds that are processed and easy to chew will help the problem of dropping feed. Water can also be added to the feed to make a gruel which will be even more edible for the horse with poor dental condition. A horse can literally “drink” a meal if teeth are in extremely poor condition.
Digestive System – As the horse ages, the motility of the digestive tract becomes compromised. One reason may be due to the fact that the horse itself has become less active. However, digestive concerns still can occur in those individuals that remain active, even as an older horse. Gas production and impactions can lead to colic symptoms. By feeding smaller meals more frequently, the horse can more easily digest and process its feed. Reducing starch or grain in the diet can be helpful in preventing excess gas and constipation. Increasing the amount of a high quality, easily digestible fiber source may also assist in this regard. As always, offer plenty of clean, fresh water to keep food moving through the system. Consider adding 2 ounces of salt to the horse’s diet to stimulate water consumption. Remember, horses prefer tepid water from 45 to 75 degrees Fahrenheit.
As part of the aging process, the older horse experiences a reduction in digestive efficiency, along with a decline in its ability to absorb nutrients. By feeding a processed feed, as opposed to whole grains, and by fortifying the nutrient levels in that feed, the horse is better able to absorb those nutrients which are made available in its diet.
Parasite infestation also hinders digestive capabilities, so a proper deworming and parasite control program must always remain paramount in proper maintenance and care of the horse at any age.
Body Weight – Though some senior horses have a problem with being overweight, it is much more common to see older horses that have become too thin. Aging tends to result in a reduction of muscle mass, along with difficulty in maintaining adequate weight. As mentioned earlier, the older horse may not absorb nutrients as efficiently as it had been able to do in its younger years, or may be experiencing problems with chewing and digesting. Monitor horse’s body weight using the established Body Condition Scoring System, paying special attention to weight over the top line, back and rib cage areas.
If your horse is too thin, feed a processed feed that contains high quality, easily digested protein and readily available energy. If the horse is too fat, minimize grain intake to control calories, yet still assure that proper protein, along with correct vitamin and mineral balance, is being maintained.
Hair and Skin – An inadequate diet is often to blame for problems with hair, skin, and hooves in horses of all ages, but is especially evident in the older horse. Regular brushing and a good nutrition program will contribute greatly to resolving these conditions. Nutrients such as protein, essential fatty acids and vitamins are particularly important, and many times are inadequate in a typical diet. Poor hair coat in older horses can sometimes be due to Cushing’s disease. This is caused by a tumor in the pituitary gland. Symptoms of Cushing’s disease include long hair coats that shed late in the year or in patches, loss in muscle mass and excessive water intake. Consult your veterinarian if you feel your horse may be showing these symptoms.
In a study of geriatric horses, over 70% of the horses over 20 years of age showed subclinical signs of pituitary or thyroid dysfunction. These dysfunctions can cause an intolerance to glucose or blood sugar. After a meal high in starch, such as cereal grains, blood levels of glucose and insulin become abnormally high. Horses with Cushing’s disease respond to diets that are lower in starch and higher in fat and fiber. With proper veterinary care and nutritional management, these horses can live for years after the appearance of the clinical signs.
Bones and Joints – As horses become older, we begin to see lameness which may be due to chronic founder or laminitis, arthritis, or stiffness from weakened bones due to demineralization. The first course of action is to obtain veterinary assistance to aid in alleviating discomfort. Depending upon the specific condition, management recommendations may vary. Nutritionally speaking, it is important to provide a nutritionally balanced diet providing more calories from fat and fiber, as opposed to starch, along with a good mineral balance.
Anemia – Anemia is a reduction in red blood cells and can occur in horses of any age for a variety of reasons. In the older horse, anemia may be the result of poor nutrient utilization, or a decrease in red blood cell production. It can also be associated with heavy infestation of parasites. By providing a palatable, easily digested and balanced feed, the horse will receive and utilize the nutrients essential to its good health. In some situations, an extra blood-building nutrient may be recommended by the veterinarian.
In summary, our large population of older horses can continue to provide us with joy and entertainment for many, many years provided that we, as their caretakers, are aware of their changing needs and make certain that we do whatever we can to provide them with the best care possible in their golden years. Through proper nutrition, management and health care, we can help our older horses to continue to thrive for many years!
When a horse is too thin, what is the best way to help him gain weight? The answer may not be the same in every situation so we need more information to make a good recommendation. First, we need to know if the horse truly does need to gain weight. Horse owners can disagree about the ideal weight or body condition for their horses and what one person thinks is too thin may be just right to another person. To eliminate opinions from the equation, we need to be working from an objective position of body condition score (BCS). The BCS establishes a score from 1 – 9 for how fat or thin a horse is; a score of 1 is a severely starved horse and a score of 9 is an extremely obese horse. With very few exceptions, horses should be maintained in a moderate body condition score of 5 – 6. Horses in this range will have no visible ribs showing but the ribs will be easy to feel. Essentially, if you can see ribs showing, the horse is too thin and if you can’t find their ribs the horse is too fat. A complete description of the scoring system can be found at horse.purinamills.com.
If we’ve established that the horse indeed is too thin and needs to gain weight, we now need to determine why the horse is underweight. We need to ask questions:
1. Is the horse being fed enough calories to support the lifestyle?
a. Is he getting enough feed or a high enough quality feed to support his lifestyle (age and activity level)?
b. Is he being fed enough hay or pasture, or is the quality of hay or pasture poor?
2. Has the horse been effectively dewormed to control internal parasites?
a. Resistant worms are becoming a more frequent problem and deworming programs that have worked for years may not be doing the job in some horses now.
3. Is there a health issue preventing the horse from properly utilizing feed or that is causing nutrient requirements above normal levels?
a. Are there dental problems due to age or inadequate dental care causing compromised chewing? Are the dental problems such that the horse can’t or won’t eat enough hay or pasture or drops a large amount of feed when eating.
b. Does the horse possibly have gastric ulcers, colonic ulcers or other inflammation of the digestive tract that is causing a decline in digestion or intake of feed and hay?
c. Is there some intestinal issue preventing proper digestion and absorption of nutrients from the diet?
Answering the first question is fairly simple and straight forward and is the easiest situation to correct. Evaluate the current diet and make appropriate adjustments to improve the amount and level of nutrition being offered. Weigh the feed and hay being fed with a scale to determine actual pounds per day the horse is eating. Compare with feeding directions on the feed tag and determine if the amount being fed is adequate for the situation. Horses should be eating a minimum of 1.0 pounds of hay per 100 pounds of body weight (10 pounds of hay for a 1000 pound horse). Horses will very often not eat all of their hay when the hay quality is poor, so be sure to weigh the amount horses are actually eating, not just what may be offered. If the hay quality is low or the horse isn’t eating at least the minimum amount, an alternative hay source needs to be located or be replaced with a bagged complete feed/hay stretcher that includes adequate fiber to replace hay. If the horse is out on pasture, the pasture needs to be evaluated to determine if it is truly grazing, providing nutrition, or is it just a place to hang out and nibble around. Pastures can have a green color to them but be weeds or poor quality grasses and not provide adequate nutrition to sustain horses in good shape. Pasture quality and nutritional values vary significantly depending on fertilization and many other pasture management and weather-related factors. On average, due to the higher water content of pasture, horses must eat 30 – 40 lbs of fresh pasture to equal the dry matter intake of 10 lbs of hay. Pastures generally should be at least 3 – 4 inches tall to provide sufficient grazing to supply adequate fiber and nutrition.
An average 1100 pound horse at maintenance requires 16,700 calories per day. This can be achieved by something as simple as 15 – 20 pounds of hay and 1 – 2 pounds of Purina® Nature’s Essentials Enrich 32®. As the level of activity or individual metabolism of the horse increases, it becomes necessary to choose a feed that will provide adequate calories when fed with the available hay or pasture that will maintain good condition. Moving a horse from a body condition score of 4 to a 5 represents around 45 – 50 pounds of weight gain. Horses can realistically gain 0.5 – 1.0 pound per day and that requires from 3,000 – 6,000 calories above the amount required for maintenance. To determine how much feed that takes requires that you know the calories per pound in the feeds. For example this requires roughly an additional 2 – 4 pounds of Purina® Strategy GX® or Omolene 200® or 1.5 – 3.0 pounds of Purina® Ultium Competition Formula®. It would take 2.75 – 5.5 pounds of whole oats to support similar weight gain.
If a horse is being fed properly and is still not in good condition a veterinarian should be consulted to help answer questions 2 and 3. Simply increasing the amount fed or even changing feeds will very likely not address these issues.
Source: Karen E. Davison, Ph.D., Equine Nutrition Specialist, Southwest Market, Land O’Lakes Purina Feed
Water is the main component of the body. In fact, an average 1000 pound horse is roughly 660 pounds (80 gallons) of water. About two-thirds of this water is inside cells, called intracellular fluid, and one-third is outside cells or extracellular fluid. To function normally, the body must keep the amount of water in these areas in balance and relatively constant. This is termed water balance. The water in the body contains dissolved mineral salts called electrolytes, primarily sodium, chloride, potassium, calcium and magnesium. These dissolved electrolytes exist as ions, which are charged particles that conduct electric currents, thus the name electrolytes. Electrolytes are used to maintain voltages across cell membranes, and are distributed through the body in a highly ordered way. Any disruption of this order can result in severe body dysfunction, including heart and gastrointestinal problems, muscle cramps and impaired brain and nerve function. Sodium and chloride concentrations are normally higher in extracellular fluid, while potassium concentration is higher in intracellular fluid. Electrolyte balance is tied very closely with water balance.
Water and electrolytes are excreted from the body primarily through sweat, urine and fecal output. The body attempts to maintain a balance between dietary intake of electrolytes and excretion rates. Kidneys adjust the volume and concentration of urine based on the water and electrolyte balance in the body through an intricate hormone signaling system. Electrolytes are not stored in the body, so the amount needed daily must be provided in the diet. If dietary electrolyte level is lower than needed, the kidneys will conserve and reabsorb electrolytes. If dietary electrolyte supply is more than needed, the kidneys will flush any excess. This very complex mechanism keeps water and electrolyte balance tightly regulated under normal circumstances. However, when the relationship between intake and output is challenged, normal mechanisms may not maintain the balance. Hard work, especially in hot and humid conditions will challenge normal water and electrolyte balance mechanisms. Under these conditions, horses can lose as much as four gallons of sweat per hour, which carries with it approximately 10 tablespoons of electrolytes – primarily sodium, chloride and potassium. Human sweat is hypotonic, meaning the concentration of electrolytes in the sweat is lower than the concentration in the blood. As people sweat, sodium concentration in the blood rises. This triggers the thirst response causing the person to want something to drink. Horse sweat is hypertonic, the concentration of electrolytes in the sweat is higher than the concentration in the blood. As the horse sweats, sodium concentration in the blood remains unchanged even though large amounts of sodium are being lost in the sweat. Without the rise in blood concentration of sodium, the thirst response doesn’t kick in. This is why dehydrated horses often show no interest in drinking, which simply makes the situation worse.
Hay and pasture contain high levels of potassium and a normal diet will provide adequate potassium to meet requirements of most horses. Usually, only hard working horses that sweat for prolonged periods need additional potassium supplementation. Most commercial horse feeds contain 0.5 – 1.0% added salt (sodium chloride) which, along with free-choice access to a salt block, will supply adequate sodium and chloride to meet requirements of horses in light activity. Horses being ridden regularly and sweating moderately on a daily basis cannot eat enough salt from a salt block to meet their needs. Providing 2 – 4 tablespoons of loose salt daily in the feed will meet the increased requirements. For horses that are sweating profusely, a mixture of ⅔ sodium chloride and ⅓ potassium chloride (Lite salt), would provide adequate sodium, chloride and potassium to replenish the higher losses. Commercial electrolyte supplements are also available, but should contain sodium chloride as the primary ingredient.
Providing daily electrolyte supplementation beyond what a horse needs to maintain balance can be very counterproductive. The kidneys will become very efficient at flushing the excess electrolytes out of the system and then on a day the horse really needs a higher level, they won’t be available. The current recommendation for electrolyte supplementation is to provide additional electrolytes the day before, the day of and the day after a horse is going to work very hard and sweat a great deal. It is also very important that electrolytes are only given to well hydrated horses. Since you can lead a horse to water but you can’t make him drink, dehydrated horses should receive fluids intravenously to be sure water balance is adequately restored.
By Karen E. Davison, Ph.D., Manager – Technical Services, Purina Mills, LLC
Tags: equine health, horse, horse health, horses and water
This entry was posted on Wednesday, August 4th, 2010 at 6:59 pm and is filed under News & Articles, News & Updates. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.
Now that the weather has finally warmed up, horse owners are starting to spend more time with their horses, and are looking forward to even more enjoyable riding weather. There are some nutritional concerns, however, during this season, and some management issues we should address to ensure the health and performance of our horses.
First, as we start working our horses more, we must increase the plane of nutrition to ensure that the horse’s increased requirements are met. Energy is possibly the most important nutrient to consider in a working horse. As a horse works harder, its energy (calorie) requirement increases, and we must supply those additional calories in a form that will not compromise the horse’s digestive health. We can add more calories by increasing the amount of grain in the ration, but grain is high in starch, and too much starch (and other soluble carbohydrates) may lead to digestive disturbances such as colic and/or laminitis. Safer energy sources include fat and fermentable fibers.
Feeds such as Purina’s Ultium® Competition, Strategy® Professional Formula GX, and Omolene #500® Horse Feed are higher in fat and fermentable fibers, and lower in starch than traditional sweet feeds, therefore are excellent feeds to increase the calories in a working horse’s diet. Omolene #200® Horse Feed is another excellent feed for these situations, as more of the calories are supplied by fat, and less by starch. These performance feeds also contain the amino acids, vitamins and minerals to support the increased demands of the performance horse. Keep in mind that all feeding changes must be made gradually, so it is important to gradually increase the amount of feed as the horse’s work load increases.
If you are not planning to ride your horse hard, however, or your horse is naturally an easy keeper, a concentrated feed such as Nature’s Essentials® Enrich 32® Supplement may be the best way to meet the horse’s nutritional needs without adding many calories. If your horse stays in good body condition (not too fat or too thin) on just hay or pasture, feeding one to two pounds of Nature’s Essentials® Enrich 32® or Enrich 12® Supplement will provide the protein, vitamins and minerals that the horse needs to stay healthy.
Next, we need to keep in mind that the forage portion of the horse’s diet may be changing, and we must be aware that some of these changes may be problematic for some horses. For some horses, the advent of spring means that the source of forage changes from hay to fresh grass. If this is the case, the horse owner should take care to minimize the risk of laminitis as horses are exposed to fresh pastures.
Why can fresh grass cause laminitis in horses? During the process of photosynthesis, plants manufacture sugars that are either used for metabolic processes such as growth, or are stored as polysaccharides such as starch or fructan. The storage form of the sugars depends on the plant species. In certain situations, such as the warm sunny days and chilly nights that we see in the spring and the fall, the plants use fewer sugars for growth, and therefore store more as polysaccharides. This can cause problems for horses, especially when the sugars are stored as fructan, because fructan does not appear to be digested in the horse’s upper gut (where starch is digested and absorbed), but instead passes into the hindgut where it is fermented by the microbes. It is this fermentation of fructan that appears to be a trigger factor for colic and/or laminitis, similar to a grain overload in horses. The fermentation of fiber carbohydrates in the hindgut is normal, and does not cause digestive disorders in the horse.
Other environmental conditions that can affect the amount of polysaccharide storage in plants include drought stress, duration and intensity of sunlight, salinity (salt content) of soil, and overall health of the plant. Again, some species of grass, including cool season grasses, tend to store sugars as fructan, while others, the warm season grasses, tend to store sugars as starch and are less likely to cause problems.
How then do we manage pastures to minimize the risk of laminitis? Horses that are kept on pasture year-round usually adjust to the new grass as it grows. Nature does a fairly good job of making the pasture change gradually. The problems usually occur when horses have been confined and fed a hay and grain diet during the winter, and are then abruptly turned out on the lush green pasture in the spring. Further, horses that have been kept up through the winter may overeat when turned out because of the palatability of the lush green foliage. This sudden change in the diet, especially when it includes a rapid influx of the unfamiliar fructan into the hindgut, may trigger digestive upset.
There are several ways to prevent or minimize problems when introducing horses to spring pastures. Feeding hay immediately before turn-out may help keep horses from overeating, since they are less likely to overeat on an already full stomach. Restricting grazing time will also help minimize risks. A suggested schedule is: thirty minutes of grazing once or twice a day on the first day of grazing; then increase grazing time by 5-10 minutes per day until the horses are grazing 4-6 hours per day total. At this point, they have adapted to the green grass.
One final consideration when getting back into the saddle is the condition of the horse. On that first warm sunny day, it is very tempting to head out to the barn for a nice, long trail ride to enjoy the great weather. However, if you have not been riding your horse regularly through the winter, your horse is not conditioned for that type of physical activity (and possibly neither are you!). To prevent muscle soreness, and possibly “tying-up”, horses should be gradually reintroduced to work. Start with slow, easy work and short workouts, and gradually increase the intensity and duration of the workouts until your horse is adequately conditioned. This will help decrease the risk of problems and injuries in your horse. It may take up to 90 days to get a horse properly conditioned for strenuous physical workouts.
Once your horse’s nutritional and management considerations are addressed, and your horse is adequately conditioned for the desired workload, you are ready to head out and enjoy the season!
Source: By Dr. Katie Young, Consulting Equine Nutritionist, Purina Mills, LLC