*NSC = starch PLUS sugar

D. J. Burke, Ph.D.
Director of Equine Nutrition
Upper Sandusky, Ohio

What is “LOW STARCH”?

Did you know that there is NO

official definition of “LOW STARCH” for horse feeds? ANY product can be called

“LOW STARCH”!!!!!! In addition, “low STARCH” ignores another major

“non-structural carbohydrate (NSC) – SUGAR!! We must consider the sugar level

of feeds as well, especially in feeds with molasses and in forages. As the

horse digests starch, it is absorbed from the intestine as sugar, so, in

effect, the horse’s body cannot tell the difference between starch and sugar in

his diet.


% STARCH plus % SUGAR level in feeds gives us % NSC. We use “ESC” (ethanol soluble carbohydrates) for

“sugar” in grains or concentrates and “WSC” water soluble carbohydrates) for

“sugar” for hay and pasture. Thus, for the balance of this article, we will use

“NSC” to more correctly represent what is commonly called just “STARCH”.

Why is “LOW NSC” important
to the horse and its owner??

The main effect high NSC intake

causes is an increase in blood glucose (sugar) levels, which leads to an

increase in blood insulin levels. High insulin levels are only positive during

emergency situations, when a horse needs to “fight or flee”.  Otherwise, high insulin levels are associated

with many negative issues in horses, such as:




    ORTHOPEDIC DISEASE (physitis, OCD, contracted tendons etc.)


Elevated insulin levels can also

make CUSHING’S SYNDROME more difficult to manage.

It is likely that many of the above

problems develop over time, especially obesity and insulin resistance. Changing

your feeding program from the traditional high-corn, high-molasses sweet feed

to a low NSC concentrate may delay the onset and reduce the severity of such


What other factors need to be considered? 


people focus on just the PERCENT NSC in a feed. The most important factor is

the AMOUNT of NSC consumed! Many

other factors impact how the horse reacts to the NSC in his diet. In

relative order of importance:

  • INDIVIDUAL VARIATION (Horse-to-horse) – the MAJOR


  • Amount of Feedstuff Consumed


  • NSC Content of Feedstuff (%


  • Rate at Which Feedstuff is

    Consumed  (i.e. Forage vs. Concentrate)

  • Processing of Feedstuff –

    grinding and/or heat-treatment increases response

Can you prove this?

The studies below were designed and funded by the Equine and Specialty Research

Team of Cooperative Research Farms (www.crfarms.org),

and were conducted at Michigan State University, East Lansing, Michigan. CRF

has conducted 5 research trials investigating the effects of NSC on both normal

and insulin resistant horses.

Two studies in particular are relevant: Effects of

Concentrate Starch Levels on the Glucose and Insulin Responses in Horses (E08 MSU27) and Effects of

Concentrate Starch Levels on the Glucose and Insulin Responses in Insulin

Resistant Horses (E10

MSU31). The purpose of the studies was to evaluate the effects of feeding

different amounts of NSC (starch plus sugar) in concentrates to normal

and insulin resistant horses on glucose and insulin response after feeding. The

four concentrate treatments were formulated to supply 0.07, 0.14, 0.21 and 0.28

pounds of NSC per 100# of body weight per meal. All horses received all concentrates

in random order.

The combined results from the two studies show that TOTAL NSC INTAKE, not % NSC is

the most important consideration when trying to manage horse with NSC-related

problems. The TOTAL NSC INTAKE is calculated by multiplying the % NSC x pounds of

feed offered per meal. (for example 4 pounds of a 15% NSC feed yields:

4 pounds x 0.15 = 0.60 pounds of NSC per meal)

Analysis of the results suggests the level of NSC intake required to minimize blood glucose and insulin responses in: 

  • horses with insulin

    resistance and/or metabolic syndrome:= 0.05 pounds of NSC per 100# of body weight per meal.

  • “normal” horses = 0.1 pounds of NSC intake

    per 100# of body weight per meal.

For example, a 1,000 lb. insulin resistant horse at 0.05 pounds per 100 lbs. of body weight (1,000 lbs. = 10 – 100 lb. units) = 0.05 x 10 = 0.5 pounds of NSC per meal. One pound of Essential K at 13.5% NSC = 0.135 lbs. of NSC Ð well below the safe 0.5 lbs. of NSC intake. Even 2 lbs. of Essential K only supplies 0.27 lbs. of NSC intake per meal.

So how do you know the NSC level of a particular feed? Currently, the NSC level is not required on horse feed tags. A few companies are providing the number, but most do not. You can try calling the company, but, again, most will not give you the information (Tribute Equine Nutrition WILL provide this information for all of our products). In addition, you should check the feeding recommendations for the feed and your particular horse. Remember, the higher the feeding rate (pounds/day) the higher the total NSC intake will be. Underfeeding the recommended feeding rate will result in reduction of the amino acid, vitamin and mineral intake the feed was designed to provide.

It is also important to recognize there is a tremendous variation from horse-to-horse in how NSC affects their behavior and/or body. In addition, horses that are working hard, growing, or lactating can tolerate higher NSC levels than the idle mature horse, especially those with known issues, like those listed below.

Also important is the RATE that a feedstuff is consumed by the horse. A critical factor in the glucose and insulin response is how much NSC the GI tract is exposed to in a given amount of time. For example, if we had a hay and a concentrate, both at 15% NSC, the horse would consume the concentrate much more quickly than the hay.  This results in more NSC hitting the small intestine per minute and thus a larger glucose/insulin response.

What else should we consider?

One must also be sure the “low NSC” feed provides all other critical nutrients, like amino acids, vitamins and minerals. Merely lowering NSC levels without providing the other critical nutrients will not maintain the horse’s overall health.
Also, to achieve a truly low NSC feed sources of fat and fiber must be used to supply needed calories. It is important that the fiber sources be highly digestible, such as beet pulp, soy hulls and dehydrated alfalfa meal. Ingredients like oat hulls are much less digestible.

Remember, the main source of intake and calories in most horse’s diets is FORAGE (either pasture, hay or some combination thereof). The main source of risk in forages is SUGAR, and in some cases, a related compound called fructan. Sugar has the same effect on NSC in the horse’s body, but forages are consumed more slowly than concentrates, which lessens the impact somewhat.

Pasture is consumed more readily and faster than hay and the sugar content is highly variable, depending on time of day and season. A good, general rule is that horse with known risk factors such as obesity, insulin resistance, laminitis etc. should NOT be allowed to graze on pasture, and should be managed on a dry lot with grass hay.

What is the answer?

The product which provides the most complete nutrition package in a true “low NSC” design is Tribute’s ESSENTIAL K. ESSENTIAL K is formulated to be approximately 13.5% NSC, with very low feeding rates (0.5 -3 pounds PER DAY depending on the horse’s size and life stage) which would afford only 0.07 to 0.42 pounds of NSC per meal. Furthermore, ESSENTIAL K provides optimal amino acid balance, higher fat, highly digestible fiber sources and vitamin and mineral levels that meet or exceed the new NRC 2007 requirements for horses. When fed as recommended, ESSENTIAL K can be LESS EXPENSIVE to feed per day than other products.

The next best low NSC alternative is TRIBUTE KALM N EZ. It is formulated at 14.5% NSC and has a minimum feeding rate of 3 pounds per day for a 1,100 pound horse. That would provide only 0.44 pounds of NSC per meal. 


Formula to calculate pounds of NSC per meal:
POUNDS FED x %NSC (as decimal); for example:
2 pounds of a 13.5% NSC feed =
2 pounds x 0.14 = 0.27 pounds of NSC

For more information and help on what to feed your horse, please see our website: TRIBUTEEQUINENUTRITION.COM or call 1-(800) 472-9507