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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

Spring and summer months bring an increase in horse activities and the end of hibernation for rattlesnakes. As they begin to emerge and leave their dens, until their return during cooler fall weather, this movement and activity increases the incidence of horses bitten by rattlesnakes. Of the 27 species of rattlesnakes in the United States, 11 are found in Texas. The Western Diamondback Rattlesnake and the Prairie Rattlesnake are the most common rattlesnakes found in the western part of Texas where veterinarians treat an average of about 6 – 10 cases per year. Over 90% of these bites occur on the face, primarily the nose, in pastures or fields while the horse is grazing. They can also receive some nose bites when the horse gets curious to the sound, site and smell of the rattlesnake. The second most common bite site occurs on the lower limbs. Rarely, horses may be bitten on the chest, abdomen, upper legs or other locations while the horse is lying down.

Rattlesnake venom contains many myotoxins and hemotoxins.  Localized signs of rattlesnake bites include significant to severe swelling, pain, and bleeding at the bite site, with significant tissue damage. Horses become lethargic and usually have difficulty breathing. Occasionally, systemic signs such as dehydration, fever and irregularities in heart rate and rhythm can be present. Shock rarely occurs. Severity of reactions may depend on the amount and concentration of the venom injected by the snake. Size, species, health, age of snake and condition of its fangs also can affect the outcome of the bite.

When a horse receives a rattlesnake bite, keeping the horse from moving or becoming excited prevents further absorption and circulation of the venom. This also limits further increases in respiratory rate through a horse’s restricted air passages. Most facial bites usually resolve with early treatment but an average of 20% of leg bites can result in chronic problems such as lameness or infection.

Rare long term complications include cardiac disease. Medical treatment is aimed at ensuring that the horse has adequate breathing capabilities. Cut off garden hoses or syringe cases can be placed a distance up the horse’s nostrils to open up the airways. Although this technique can be a useful tool, some horses won’t tolerate it because their nose is too painful and/or they are frightened by the procedure. Medications used by veterinarians include steroids and non-steroidal anti-inflammatory drugs to decrease swelling around the bite site. Tetanus prophylaxis also is indicated. Antibiotics are used as well as local wound therapy on leg bites. Wetting hay and feed for horses with facial bites can help them eat.

By Ginger Elliot, DVM, Guthrie, Texas

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

When a mare foals, her daily nutrient requirements increase significantly, nearly double that of early gestation. These nutrient needs must be met for the mare to recover from foaling stress, produce milk, and rebreed without losing body condition. Underfeeding mares during early lactation will result in lower milk production and weight loss. Early lactation weight loss, especially in mares that foal in thin condition, will likely affect the mare’s ability to raise her new foal and become pregnant again. Mares produce an average of 24 pounds (3 gallons) of milk daily during a 5-month lactation period. This represents 450 gallons or 1 3/4 tons of milk over 150 days. High producing mares yield as much as 32 pounds (4 gallons) of milk daily. Production appears to peak at 30 days and then slowly decline. Nutrient content of mares’ milk follows a more drastic downward curve. In the fourth month of lactation, a mare’s milk provides less than 30 percent of the total energy needed by her foal. Providing lactating mares with a feed such as Purina Omolene 200 or Strategy that includes added fats or oils and high quality protein can help slow the downward curve of production and improve nutrient content of the milk. This will translate into an early growth advantage for the nursing foal.In the fourth, fifth and sixth months of lactation, daily nutrient requirements of mares begin to decrease along with declining milk production, but nutrient requirements of the foals are increasing. Foals should have had access to a properly balanced foal feed, at the rate of one pound per month of age per day, beginning within a few days of foaling. Once the foal is 4 months old, it is more nutritionally accurate for the foal and more economical for the horseman to feed the foal a quality diet to meet his needs than it is to feed the mare to produce milk. Once the foal is weaned, the dry, pregnant mare can be managed as an early gestating mare once again. Through proper health care, feeding management and breeding techniques, the mare can produce a strong, healthy foal each year.

Source: http://www.aaep.org/health_articles_view.php?print_friendly=true&id=119

In the past several years, multiple sources have recommended yeast products for inclusion in equine diets for many purposes, including improving fiber and phosphorus digestibility, increase feed efficiency, support hindgut bacteria, and even prevention and cure of gastric ulcers. However, a close look at the published data available on the efficacy of supplementing yeast culture in the diets of horses does not support the claims of positive effects in horses fed quality diets that meet nutritional requirements.

AAFCO defines a number of yeast products as feed ingredients, including dried yeast, yeast culture and yeast extract. Dried yeast may be either active or nonfermentative. Yeast culture is a dried product composed of viable yeast cells and the media on which it was grown. Yeast extract is a dried or concentrated product of cell contents from ruptured yeast cells.

Studies in ruminants suggest that addition of yeast products to ruminant diets promote bacterial growth in the rumen. It is generally believed that yeast additives either directly facilitate fiber digestion and dry matter intake, or contain metabolites or compounds that stimulate bacterial growth to facilitate fermentation and animal performance in ruminants. Since horses have fermentative capability in the hindgut, it has long been proposed that yeast products may have beneficial effects on digestion/fermentation in the hindgut, resulting in enhanced fermentation and increased fiber and/or nutrient digestibility.

According to the 2007 National Research Council’s Nutrient Requirements of Horses, “Unlike observed effects in ruminant studies, supplementation of yeast in horse diets tended to show some beneficial effects on fermentation, but results were equivocalacross studies.” There is great variation in published results of feeding yeast products to horses – most studies report minimal to no increase in cecal or colonic bacterial cultures as a result of feeding yeast products, although a few studies have reported beneficial effects when yeast products were fed with very high starch diets, or with low quality forages. Some studies have reported no improvement in nutrient apparent digestibility when yeast products were fed to mature horses, but others have reported some improvements in fiber and nutrient digestibility. However, the reports of improved digestibility of nutrients with the addition of yeast products are most often seen when yeast products are added to nutritionally deficient diets. The Purina Equine Research team recently completed a thorough, long-term study that looked at the efficacy of yeast in enhancing fiber digestion in horses, as well as several other parameters, and the data indicated no effects of yeast on fiber digestion. This data is currently being prepared for submission for publication in a scientific journal. However, ongoing Purina research continues to investigate potential effects of yeast products on other parameters of equine digestion, health and performance.

Yeast products can be a source of quality nutrients, including essential amino acids and B-vitamins, so adding yeast products to a nutritionally deficient diet will result in improved performance in horses, just as addition of any ingredient that supplies deficient nutrients to a ration will result in improvement in performance. However, when yeast products are added to diets that are nutritionally balanced and fortified to meet a horse’s nutrient requirements, the additional nutrients provided by the yeast products have not shown measurable benefit. At this time, there is insufficient data to support the inclusion of yeast products in horse feeds for benefits other than those simply provided by the nutrient content of the yeast products, and there are many other feed ingredients that provide quality nutrients for optimal nutrient content in horse rations. Purina Premium Horse Feeds are nutritionally fortified and balanced with quality protein sources as well as specific essential amino acids, minerals and vitamins to meet horses’ nutritional requirements when fed as recommended. And, of course, if and when we elucidate beneficial effects of yeast products in horses, we will share those findings with our customers and add them to our feed formulations.

Katie Young, Ph.D. Land O’Lakes Purina Feed

Heat and humidity put an added burden on horses during training, showing and hauling. Horses are actually better equipped to work in cold weather than in the heat. They build up a tremendous amount of body heat due to the internal heat produced by fiber digestion and the large mass of working muscles, combined with insulation from their hair coat and body fat cover.

Normal body temperature for a mature horse at rest is 99 – 101° F. Under working conditions this can rise to 102 – 104° F, but with the same work under hot, humid conditions body temperature can elevate dangerously to 106 – 107° F. Body temperatures of 104° F or higher for any extended amount of time can be life threatening.

A horse’s main cooling mechanism is evaporation of sweat from the skin surface. Increased blood flow in the veins and capillaries close to the skin and elevated respiration rate help dissipate internal heat as well. Increasing humidity reduces the evaporation of sweat from the skin, thereby decreasing the cooling ability. Under extreme heat, especially when humidity is high, the body’s cooling mechanisms may not work well enough to dissipate the heat generated. This can lead to heat stress which is hard on the body and can impair performance.

A simple calculation of Ambient Temperature (° F) + Relative Humidity (%) – Wind Speed (mph) will indicate heat stress risk level. For example, ambient temperature of 98°F with a 55% relative humidity and wind at 5 mph; 98 + 55 – 5 = 148. If the calculation equals 130 or less, then the horse’s own cooling mechanisms will work effectively. Between 140 and 170, the horse has partial cooling capacity and may need some assistance cooling down. When the result is greater than 180, the horse has a significantly impaired ability to cool and is at high risk for heat stress or even heat stroke.

Horses unaccustomed to the heat or those not properly conditioned will sweat more for a given amount of work than fit or acclimatized horses. While it is necessary for horses to sweat to help cool the body, sweat generated during work robs the body of fluids and important nutrients that must be replenished. Horse sweat is more concentrated than human sweat, meaning it contains a higher concentration of electrolytes. Electrolytes are electrically charged mineral salts that play a large role in water balance and are integral to nerve and muscle function. An electrolyte imbalance can lead to heart problems, digestive dysfunction, muscle cramps and nervousness. The primary electrolytes lost in equine sweat are sodium, potassium, and chloride.

Horses working at light to moderate levels will receive adequate electrolytes from nutritionally balanced feed, good quality hay and a salt block or a couple ounces of loose salt per day. Even if these horses are sweating a bit, a good diet along with clean water will replenish everything lost in the sweat. However, horses working very hard in hot, humid climates and sweating a great deal may need additional electrolyte supplementation.

Electrolyte supplementation should be approached carefully. First, never give electrolyte supplementation to an already dehydrated horse. Second, the body has a set requirement for electrolytes but doesn’t store any extra. If supplemental electrolytes are provided in excess amounts, the body will become very efficient at eliminating them in the urine. This causes the horse to urinate more frequently, thus increasing water needs and making it more difficult to stay hydrated. Also, if the body is flushing excess electrolytes out of the system to keep the balance, on a day when additional electrolytes may be needed, they won’t be available. Therefore, the best recommendation is to p

rovide a well balanced feed, good quality hay and free choice salt and water on a daily basis. Provide additional electrolyte supplementation the day before, the day of, and the day after an event in which the horse works

extremely hard and sweats excessively. There are many commercial electrolyte supplements available, or a home-made mix of 3 parts salt (sodium chloride) and one part lite salt (potassium chloride) is an option. Remember though, for the vast majority of working horses, the sodium and chloride requirements can be met with a couple ounces of plain salt per day and the potassium, calcium and magnesium requirements will be met by a well balanced quality feed and hay. Therefore additional electrolyte supplementation is needed only at those times when a horse will be sweating large amounts for an extended time frame.

By Karen E. Davison, Ph.D., Manager – Technical Services, Purina Mills, LLC