Why should horse owners know how to read a hay test?

“I’ve just bought hay for my metabolically challenged horse. I was told the hay was ‘low sugar’ and possibly the sugar was ‘below 10.’” What does that mean?

As owner’s it is our responsibity to advocate for our horses. We make all the decisions that affect their health. We chose where they live, what they eat, when they eat, when they excersize. We control their access to water! In this same vein, its up to us to understand what they eat. As owners it’s not good enough to buy hay because the girl at the feed store says it’s the right choice.

More and more owners are choosing to buy and feed their equine companions tested hay. This is a wonderful shift, using science to make decisions about what is the best feed. Once upon a time we chose our hay based on the smell, colour, possibly the cut and species we believed was best. While smell is still important, hay should be clean and free of noxious weeds, mold, dust etc., colour has no significant impact on nutritional value. Cut and species means very little in terms of protein, in terms of caloric content or overall nutritional quality. A hay analysis gives us the right information to make a truly educated choice.

But what if you don’t understand the test? Worse, what if a seller tells you there is a test but you never really see that test? And because you don’t know how to read it you never push for a copy as its useless to you? Learning to “read” a hay analysis really isn’t hard. There are a few important numbers, especially for those who feed metabolic horses. Sugar of course, by now most people know sugar should be low for a horse that has metabolic syndrome, Cushing’s, is prone to laminitis or a horse that is simply thrifty and tends to run to fat. But what does that mean? Low sugar, I see hay advertised as low sugar all the time. It’s become a buzzword, a catch phase if you will, an advertising ploy. There are still people who “don’t believe” in the low sugar “craze” and will outright lie in order to sell you hay. And, again there are people selling hay who don’t know how to read a test either. The person who sold them the hay may have told them that it is low sugar. They just pass on that statement with nothing to back it up. There are still many people who don’t know which of the various measures of carbohydrate values to reference when trying to determine if a given hay is adequately low sugar for your horse so may inadvertently sell you hay they believe to be suitable when it is not. What does low sugar mean?

Sadly, I have seen horses become extremely ill because someone thought an ESC value below 10 meant the hay was low sugar. After all ESC does refer to carbohydrates and many people now know the “sugar” in hay should be below 10 to be safe for a horse with laminitis. There are several numbers on a typical hay analysis which denote carbohydrates. While the average horse owner is probably fine not knowing the intricacies of each type of sugar, it’s important to have an overall understanding of what the various numbers refer to and more importantly what those values should be for your horse. What is the difference and why does that matter?

ESC, WSC and starch are the three measures we typically see on a test that give us the overall picture of carbohydrate levels. ESC refers to ethanol soluble carbohydrate, this is a measure of the very simple sugars stored in the plant. WSC stands for Water Soluble Carbohydrate, this is the ESC plus more complex sugars found in the plant. If the difference between the WSC and ESC is calculated this gives us an idea of fructan levels. Forage testing labs are not yet testing for fructans directly but we can use this equation to get an idea of how much fructan has been stored. Starch is yet another complex form of sugar used by plants to store carbohydrates.

Some hay analysis will also provide an NSC value. The NSC is equal to ESC + fructan + starch.

So what does that all mean? Thankfully we can view these numbers and notations in a much simpler form:

NSC = WSC + starch

NSC is the value we want to concentrate on when talking about sugar in hay. This gives the total carbohydrate value, simple and complex sugars combined. This is the value we want to be as close to or below 10% for a horse with metabolic syndrome as we can possibly find.

Nutritionist Shelagh Niblock has created this wonderful graphic to help us decipher our hay analysis. When you obtain your hay test from the lab or your hay supplier you can simply reference these numbers she has provided. You’ll note she has also offered ranges for horses who are not suffering from metabolic syndrome. Not all horses need or will thrive on a low sugar hay, it is important to remember carbohydrates are energy but that is a topic for another post.

As much as I appreciate the great trust my clients place in me to provide nutritionally appropriate hay for their equine partners I think it is important we all have a basic understanding of a hay analysis, especially for those feeding the more sensitive horse. At Wrayton Transport we publish hay tests for all the hay we sell so you can see for yourself exactly what you are feeding.



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