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Nutritional Updates in Equine Nutrition
Since the publication of the 1989 Nutrient
Requirements of Horses by the National Research Council (NRC) more information
has become available to better help us address the nutritional needs of horses.
These needs vary greatly depending on the age, reproductive status, and
activity level of the animal. The
main emphasis of this article will focus on some of the more recent research
that has come available regarding energy, vitamins, and some minerals for the
performance horse. Energy Energy is not a nutrient. It is the capacity to do work. Feedstuffs are measured based on their ability to provide energy to an animal for daily functions. Active horses often have energy requirements that result in the need to feed diets high in concentrates. This can sometimes result in gastrointestinal problems such as colic. As athletic ability continues to improve through genetics and training, nutritional needs must also keep pace with these improvements. Studies over that past few years have indicated that rations higher in fat content can help improve performance and reduce incidences of colic caused by high concentrate diets. Fat in the diet produces a glycogen sparing effect that increases glycogen stored in the muscle. This glycogen can then be readily converted to energy under anaerobic conditions such as occurs in race and cutting horses. However, adding fat today won’t create a
derby winner tomorrow, but it may help maintain body condition on hard working
horses. There are several factors
that should be considered when adding fat to a diet.
First, there is typically a three-week adaptation period needed before
the horse begins to fully utilize added fat.
Second, daily feed intake must be decreased if the work level and body
condition are to remain the same. Thirdly, as feed intake is reduced diets must be reformulated
to insure that all of the required nutrients are being met. Vitamins Vitamin requirements are not well
established in the horse and are also effected by age, reproductive status, and
activity level. The current NRC has
established estimated requirements for vitamins A, D, E, thiamin, and
riboflavin. Recent research has
shown that other vitamins also play critical roles in health and development. Vitamin A plays an important role in
maintaining epithelial cells, hooves and night vision.
Recent studies indicate that depletion of vitamin A reserves occurs when
green forages are not available and have indicated that the requirement should
be two to five times the recommended NRC level.
There is also speculation that exercise increases the need for vitamin
A. Vitamin D plays an important role in the
absorption, metabolism, and transport of calcium.
Horses with adequate exposure to sunlight each day may always be able to
meet their vitamin D requirement, but horses confined to indoor housing and
intensive work should be supplemented. Activities
that stresses bone structure, such as intensive training, carrying and jumping
will increase the amount of bone remodeling and thus could increase the need for
added vitamin D. Increasing vitamin
D has been shown to increase efficiency of calcium and phosphorus absorption and
could thus help strength bone integrity during times of stressful exercise. Vitamin E is involved in intracellular
respiration, membrane integrity, and functions as an antioxidant.
Studies have indicated exercised horses that are stalled and fed hay tend
to have low vitamin E levels, therefore supplementation is recommended for
horses that do not have access to pasture.
Also, as activity level increases, vitamin E requirements increase. Research has shown that vitamins K, C, and the B complexes also play important roles in animal health and performance. These vitamins, under normal circumstances and diets, are synthesized by the animal itself or obtained through the feed sources. More research is needed on these vitamins to determine actual requirements. Recent studies have indicated that supplementation of these vitamins may be beneficial, particularly during times of stress caused from exercise and disease. Also, biotin has been shown to improve hoof health and integrity. Minerals Minerals can be divided into two major
groups. The macrominerals, calcium,
phosphorus, magnesium, sodium, potassium, chloride, and sulfur, and the
microminerals or trace minerals, copper, iodine, iron, manganese, selenium, and
zinc. Horses are able to obtain
most of their mineral requirements from their diet under normal conditions.
However, growth, reproduction, age, and exercise increase greatly the
requirements of many these minerals. It
is not the intent of this article to discuss all of the functions of these
minerals but to highlight some of the more recent discoveries. Calcium and phosphorus are involved in bone
formation and maintenance, nerve conductivity, muscle contraction, and energy
metabolism, as well as many other important body functions.
Growing horses, especially those involved in intense training have higher
calcium and phosphorus requirements. Data
from the race horses industry indicate that musculoskeletal injuries continue to
be a major concern. More research
is needed to determine the actual calcium and phosphorus requirements of horses
under these kind of training and working conditions. Magnesium is involved in skeletal
development and is an activator of many enzymes.
There has been little research on the effects of magnesium on performance
horses. Horses grazing lush, new
growth pastures do not appear to be susceptible to grass tetany like ruminants. Sodium, chloride and potassium are involved in biochemical, physiological, and neurological functions of the body. These three minerals are essential for movement of specific ions across the cell membrane, enzyme stability, and for maintenance of the ionic and osmotic balance of intra- and extracellular fluids. Sodium and chloride are the major ions found in extracellular fluids. Sodium is the major electrolyte involved in maintenance of acid-base balance and osmotic regulation of body fluids. Chloride is an essential component of bile and is important in the formation of the hydrochloric acid used in the digestion of feedstuffs. Intake of sodium and chloride increases the absorption and retention of calcium and phosphorus. Horses do have the ability to secrete the
hormone aldosterone, which can help improve absorption of sodium during times of
reduced sodium intake. This is done
by reducing its excretion in urine, milk and sweat. This does however come at a price. When sweat production is decreased in an attempt to retain
sodium, there is an increased risk of hyperthermia during exercise. This reduces
the rate of work and thus the performance ability of the animal.
There is also evidence that electrolyte losses and imbalances contribute
to tying up syndrome in some horses. Potassium is the major intracellular cation and is also involved in the
maintenance of acid-base balance and osmotic pressure.
This high concentration of intracellular potassium plays a critical role
in the triggering action potentials that initiate muscle contraction and nerve
impulses. Exercise results in a
rapid outflow of potassium from skeletal muscle resulting in a rise in plasma
potassium. This rise in plasma
potassium aids in blood flow to working muscles. Potassium deficiency is more likely to occur
when horses are maintained on a high grain, low forage diet, the typical type of
ration fed to horses that are in training or performance activities.
Deficiencies result in muscle weakness, fatigue, and exercise intolerance
along with decreased feed and water intake.
It is important to note that most salt blocks do not contain potassium. Excess quantities of theses electrolytes are
normally excreted in the urine. Access
to clean fresh water should also be made available at all times.
The myth that hot horses will over drink and get colic simply is not
true, actually limiting water can result in colic.
Horses will recover from dehydration much quicker if they have access to
as free choice water. Trace mineral research has increased since
the publication of the current NRC. However,
little data is available for the requirements of performance horses.
Much of the recent research has focused on the requirements of the
growing animal. Copper supplementation of mares above
current NRC levels has been shown to reduce bone and cartilage abnormalities in
their foals. This could result in
improvements in skeletal development in growing animals. Iron supplementation appears to be on the
increase. There is little data to
show any benefits from supplemented iron in healthy horses.
In fact, oversupplementation of iron may affect the availability of other
minerals in the diet. Manganese is involved in bone formation and
the synthesis of chondroitin sulfate, which is necessary for cartilage
formation. Manganese is also involved in the activation of several enzymes and
in fatty acid synthesis. Simply
stated, manganese plays an important role in a horse’s ability to create
energy. Horses on hay and
concentrates, and diets high in calcium and phosphorus may require manganese
supplementation. Selenium is important in the maintenance of
membrane integrity, growth, reproduction and immune response. Studies have shown that exercise induces oxidative stress
resulting in the creation of free-radicals such as peroxides.
Increased selenium can help reduce tissue damage caused by these free
radicals. Zinc is a component of many of the
metalloenzymes in the body. Recent
studies would suggest that zinc requirements are greater than NRC
recommendations in growing animals. This
may also be the case with horses involved in strenuous exercise.
Horses appear to be tolerant to excess zinc in their diets. Zinc has also been shown to improve hoof integrity in cattle. Continued research is necessary to establish accurate requirements in all classes of horses. Vigortone Ag Products has been involved in trying to meet the needs of horses and all livestock for 90 years. Triple V horse products are designed to help meet the requirements of your horse. References Pagan, J.D. 2000. Micromineral Requirements
in Horses, Advances in Equine Nutrition, Proceedings for the 2000 Equine
Nutrition Conference for feed Manufacturers. 107. Potter, G.D., and P.G. Gibbs. 1994. Feeding
the Performance Horse. Texas A&M University Department of Animal Sciences. Crandell, K. 2000. Vitamin Requirements in
the Horse, Advances in Equine Nutrition, Proceedings for the 2000 Equine
Nutrition Conference for feed Manufacturers. 95. Hintz, H.F. 2000. Macrominerals – Calcium,
Phosphorus, and Magnesium, Advances in Equine Nutrition, Proceedings for the
2000 Equine Nutrition Conference for feed Manufacturers. 121. McCutcheon, L.J. 2000. Macrominerals-
Sodium, Potassium and Salt, Advances in Equine Nutrition, Proceedings for the
2000 Equine Nutrition Conference for feed Manufacturers. 133. National Research Council. 1989. Nutrient Requirements of Horses. Washington D.C.: National Academy Press. For more information, please call us at 1-800-553-1712 or email us at contactus@vigortone.com. Dale Carr can be reached at dcarr@vigortone.com. |
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