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NSC... Why is it important? Brought to you by Stance Equine

May 2011 by Dr Tim Kempton, Stance Equine

Dr Tim Kempton, Stance Equine.  All feeds contain carbohydrates. Carbohydrates include the fibre, and sugars and starch. The fibres are the STRUCTURAL CARBOHYDRATES that hold the plant up. These fibres are both digestible or indigestible. Look at your horse’s manure. Take some and wash it in a bucket. What you see is the indigestible fibre from the feed. Horse’s manure is drier than cattle because they do not digest fibre as well as cattle, and because they absorb more water from the hindgut.

The sugars and starch in plants are called the NON STRUCTURAL CARBOHYDRATES or NSC. The NSC in feeds is the same as the Glycaemic Index (GI) in foods for humans.

Why is NSC important?

Obesity is now a major health issue in people in the western world. Obesity in humans is linked to high intakes of sugar and starch, ie to high GI foods. Obesity is now also one of the major health problems is companion animals (horses, dogs and cats), and is directly related to over consumption of sugar and starch, ie to high NSC feeds.

High levels of NSC may have serious impacts on the health of some horses, and in particular on insulin resistance and Cushing’s disease, EMS, tying up, laminitis, fizzy behaviour, ulcers and colic.

It is believed that high NSC causes increased circulating levels of blood glucose and blood insulin after a meal. NSC is therefore important, as it is an indicator of the potential of the diet to increase blood glucose and insulin.

How do I test NSC in feeds?

NSC is determined by analysis at the Dairy One Forage Services Laboratories in the USA. Feed samples can be sent to the USA for analysis. For details see www.dairyone.com/Forage/default.asp.

NSC is calculated from the starch and WSC (water soluble carbohydrate) content of the feed.

Feed samples can be sent to the USA for analysis. For details see www.dairyone.com/Forage/default.asp.

NSC is calculated from the starch and WSC (water soluble carbohydrate) content of the feed.

Is measuring NSC enough?

NSC is the measure of the TOTAL sugar and starch in the feed, and does not reflect the DIGESTIBILTY of the starch in the horse, ie how much that is eaten passes out in the dung.

In a kikuyu pasture trial (Richards et al unpub), horses were fed either CoolStance copra, a Pelleted feed or Sweetfeed. Digestibility of the starch was determined and it can be seen that although the Sweetfeed had a high NSC (34%) it only had a digestible NSC of 21%. This means that a considerable amount of the starch was passing undigested in the dung.

All grains contain starch granules, and the structure of the starch granule varies between types of grains.
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The starch granules in maize are smaller and more slowly digested that those in oats wheat and barley.

The NSC available to the horse will therefore depend on the type of grain used.

Effects of NSC on Glucose and Insulin.

In the kikuyu pasture, feeds with various levels of NSC were fed to grazing horses (Richards 2010). These included a sweetfeed , a pelleted feed and CoolStance copra meal. The supplements were fed in nose bags in two equal feeds morning and night (pulse fed) to ensure all the food was eaten.

Circulating glucose and insulin were measured for 6 hours after pulse feeding.

In Graph 2 it can be seen that there was a glucose spike after pulse feeding the sweetfeed and pelleted feed. (Richards, N. et al, 2011 in press)

The CoolStance copra meal (NSC 11%) did not increase blood glucose levels above that in the pasture fed horses.

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What does this mean?

If you are concerned about your horse being overweight, under worked, or susceptible to any of the metabolic disorders, you should consider the NSC content of your feed, and how it is fed.

Select feeds with a low grain (low starch content) with a NSC content less than 12%. If you are actively working your horse, you must also select a feed with a high non grain energy content. This is usually provided by oil rather than grain.

Feeding twice a day is not normal, since horses graze almost continuously. Pulse feeding of grain based feeds and can cause glucose spikes as shown above. Select a feed such as CoolStance copra that does not cause a glucose spike.

What level of NSC is safe?

While a ‘safe’ NSC content has not been formally established for metabolically sensitive horses, a level of <10% to 12% NSC seems to be generally accepted as safe for metabolically sensitive horses.

Feeds with levels of NSC >20% should almost certainly be avoided for these horses.

 

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ABOUT THE AUTHOR: Dr Tim Kempton has a degree and PhD in the basic and applied aspects of nutrition. He is a horseman, and specialises in the relationships between nutrition and performance of animals. Dr Kempton has the unique opportunity to draw on experience across many species, and pioneered the concept of ‘cool feeds” for horses in Australia. He introduced copra meal into Australia in the 1980’s, which is now fed extensively as a cool feed for horses.  More recently, he has researched the role of NSC in horse feeds, and the possible effects on health and performance of horses. Dr Kempton is committed to providing equine education and products based on sound science to avoid harming our horses with kindness, through overfeeding and underworking.