THE SCIENCE BEHIND STARCH
“In the hindgut, starch is rapidly fermented,” explains Holly. “This produces gas and lactic acid, which can upset the delicate balance within the hindgut, potentially causing colic symptoms. The hindgut hosts a whole ecosystem of living organisms that are designed to ferment roughage and produce many beneficial products for the horse. When the balance is upset some of these organisms may die. This death can release toxins that may enter the bloodstream. This has been linked with the development of laminitis. Higher levels of starch fermenters in the hindgut also mean that the hindgut will not be digesting roughage optimally. This can also affect the horse’s ability to maintain their optimum condition.
“We also need to consider horses that may be overweight, at risk of EMS and/or prone to laminitis,” continues Holly. “Higher starch feeds may also be higher in simple sugars. These feeds may cause a higher glycaemic response which then triggers an insulin response. If your horse has access to high sugar/starch feeds it may be at risk of developing insulin resistance (equine metabolic syndrome). This is very similar to Type 2 diabetes in humans and is a risk factor for developing laminitis.
It is a common belief that starch contributes to ulcer formation, however, research does not support this. Starch mainly wreaks havoc in the hindgut of the horse, not the stomach where ulceration mainly occurs.
“There is currently no strong evidence to suggest a horse that is prone to ulcers cannot manage some starch content in its feed. As long as their diet is balanced, providing sufficient roughage and the starch level is appropriate it should be okay to feed to a horse prone to ulcers.
“To avoid a high starch feed, look at the ingredients and the nutritional analysis of the feed. Search for the inclusion of cereal grains and fibre percentage. In general, anything that contains less than 10% fibre will be quite high in starch. You want to be looking for something that is less than 30% starch. You do technically need to take into account protein and fat percentage but as a general rule, aim for more than 10% fibre. Specific cereal grains that are free or low starch to look for include lupins, sunflower seeds, faba beans, canola meal, soybean meal, and lucerne meal among others.”
A GUIDE FOR STARCH LEVELS
- <10% = low starch feed. Usually suitable for laminitis prone/EMS/Cushings or hot and fizzy horses.
- 11-20% = Medium starch feed. Suitable for most horses. Generally, quite good at maintaining a horse’s condition whilst also keeping them cool.
- 20-30% = Medium-high starch feed. Suitable for horses that struggle to maintain their condition and are not prone to hot and fizzy behaviour, and horses that may need a little extra energy.
- >30% = High Starch feed. Suitable for horses that require high energy. Normally utilised for high-performance horses and racehorses. EQ
This article was written in conjunction with Hygain.
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Gary’s Guide to Building Lean Muscle – Equestrian Life, November, 2021
In a Bind: The Role of Toxin Binders – Equestrian Life, October, 2021
Hold Your Horses: Feeding for Coolness – Equestrian Life, September, 2021
The Importance of Vitamin K – Equestrian Life, August, 2021