This post was originally published back in January 2011, but I have had a number of questions regarding the overweight horse and carbohydrates in equine nutrition. As a result, I am reposting. If possible, print out the Equine Condition Scoring Chart and keep it handy at your barn for easy reference. As horses are out in pasture during this time of year, we may want to review what we feed our horses so that we don't have potential future problems.
In recent years, nutrition focus has seemed to have shifted to weight management and exercise for both people and horses. I know that since I have been in the United Kingdom and not riding my horses back home, both Bruq and Phantom have gained weight due to a lack of a regular exercise routine. As a concern to me, there are some breeds of horses, such as the Arabian and Morgan, that are prone to such diseases as Insulin Resistance (IR) and Cushing's, while other breeds can be put at risk to many diseases resulting from being over weight.
My previous posting provided you with an Equine Condition Scoring Chart where you are able to score your horse from 1-9, one being deathly thin and 9 being obese. Once you have determined your horse`s condition score, you can take the necessary steps to correct these conditions, or keep him at the optimum level.
The term "low carbohydrate" diet in humans has become so very popular with the Atkins and South Beach diets focusing our attention on low carbs, and as a result many horse owners are also concerned about carbohydrates in their equine nutrition program. Happily, there has been recent research addressing the area of carbohydrates in equine nutrition and many feed companies are posting these values on their labels. However, it is very important to keep in mind that when we look for low carbohydrate diets for our horse families, we also need to look at the sugar and starch levels as well in the feeds. These feedstuffs include forages (hay and pasture) as well as the ingredients that make up the concentrated feeds that we offer our horses. These concentrated feeds include oats, corn, barley, beet pulp, soybean meal and the list goes on.
Nonstructural carbohydrates (NSC) are the sugars and starches found inside the plant cell of horse feeds. This is in contrast to the structural carbohydrates that compose the cell wall of the plants that our horses eat. The two main cell wall components are cellulose and hemicellulose, we know it as fibre. This plant fibre is disgested thanks to the work of bacteria and protozoa living in the horse's large intestine. The horse receives his energy supply by taking up or absorbing nutriants or organic acids in his large intestine. The bacteria in the hindgut (large intestine) produce organic acids from the fermentation of sugars that are released when the fiber is broken down by enzymes secreted by the bacteria and protozoa.
The sugars found in forages include glucose, fructose, sucrose and fructans. Starch is the major carbohydrate stored in the legumes of alfalfa, and warm season grasses such as bermuda grass and grains. Fructans are the water-soluable sugars that are stored as the major carbohydrate in cool season grasses such as orchardgrass, fescue and timothy.
Research has shown that excessive intake of fructans from pasture grasses and grains can cause colic and laminitis (Hoffman et al, 2001). The greatest danger of laminitis and founder for horses is the consumption of cool season grass pasture and hay which may contain high levels of sugar, especially large amounts of fructans. Legumes or warm-season grasses contain little to no fructans. For more information on the NSC value and fructans in grasses go to www.safergrass.org. It is recommended that controlling the dietary NSC value to below 20% of the total diet is appropriate for problem horses afflicted with Cushing's Disease, insulin resistance and equine diabetes (Longland & Byrd,2006) .
The table below outlines the sugar, starch and NSC values for feeds typically fed to horses. It is interesting to note that the lowest NSC values are for soybean hulls, beet pulp, alfalfa and the highest NSC values are corn, oats and barley (COB) a food which is frequently fed to horses. So, it would be safe to say that grain based horse feeds will contain a higher NSC value than feeds based on beet pulp, soybean hulls and alfalfa meal. For more information about NSC content of forages, please visit www.equi-analytical.com.
Average Sugar, Starch and Non-Structural Carbohydrate (NSC) Values of Selected Feedstuffs*.
*Values are from Equi-Analytical Laboratories, Ithaca, NY, reported on dry matter basis.
If you have a problem horse and want to implement a low NSC value feeding program, it would first be necessary to estimate the NSC content of your pasture or hay. However, having said that, sampling for the NSC content of your hay would not be practical if you do not have a supply that would last you several months. If pasture is available for your problem horse, it may be necessary to remove him or reduce his grazing. One surprising finding on current research concerning NSC levels of various hays was that alfalfa hay and alfalfa pellets had lower values than grass hay, so alfalfa hay may become the first choice for problematic horses (Geor, 2007).
Understanding nutrition and NSC values is difficult at best. We can only strive to look to research to help us make proper, informed decisions regarding the safe nutrition of our horses. One thing that I do know is that there is a great deal of research and people knowledgeable in the field of equine nutrition that can be accessed to help us with our equine nutrition program.