A quick and dirty math lesson

I have been asked several times in the last week how to find or where “where do you see” the NSC on a given hay test. What is NSC and how do you find it on your test?

I think by now that we all know what NSC is and why those with metabolically challenged equines need to be concerned with this portion of forage, any feed for that matter. We recently tested one of our own ponies for EMS, it was quite cool and I will share that adventure in another blog post shortly. However for today lets start with a quick review of the various carbohydrate (sugar) values you may find on your hay test.

ESC stands for ethanol soluble carbohydrate. These are the very simple sugars.

WSC stands for water soluble carbohydrate and are made up of the ESC and the more complex carbs.

Starch is just what it sounds like, it is starch, a complex storage form of carbohydrates. Cool season grasses, those grasses we generally find in our hay here on the coast, such as timothy and orchard grass, do not use starch and therefore the content is generally very minimal in forages.

NSC stands for non-structural carbohydrate. This is the number we usually refer to when talking about”sugar” in hay. This value is not tested for but is a calculation of other values so not all hay analysis will list the NSC specifically, sometimes we have to do that math ourselves. At Wrayton Transport we normally provide the NSC value on all our tests, if the lab has not provided it we just make a note on the side (see the tests below.)  If you receive a test and the NSC is not listed you can use a simple calculation to determine the value.


NSC = WSC + starch

You will sometimes see hay tests WITHOUT a WSC value. A test like this is useless for the purposes of calculating sugar to determine if a given hay is safe for your horse. You want to ensure the test you receive shows the WSC value and starch EVEN IF you are given the NSC. This is because we can do another calculation to determine fructans.

Fructans are a storage form of carbohydrates that are heavily implicated in laminitis in horses. Fructans are found in grass hay not legumes such as alfalfa. This is why you will often hear that alfalfa is naturally low in sugar. Labs are not yet testing specifically for fructan but we can do a another simple calculation to give us a pretty good idea of the fructan content of our hay. The fructan content of hay can be determined by the following calculation:

Fructans = WSC – ESC

So there you have it, this is the simple math you can do to determine the suitability of a given forage for you unique equine partner.



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