Horse Grain-Triple Crown Reviews Horse Grain Processing Techniques

Reviewing Different Types of Horse Grain Processing
by Amy Gill

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One of the most delicate areas to balance is the safe feeding of horses that must consume high concentrate rations to meet their energy requirements. Often, performance horses require over 50% of the diet as concentrate to maintain body condition. This type of diet makes horses prone to gastrointestinal and other metabolic disorders such as Recurrent Exertional Rhabdomyolysis (“Tying Up”). In addition, some horses are sensitive to increases in blood sugar and exhibit a “grain high”, often becoming less tractable and excitable when fed high grain diets. In the past twenty years, nutrition research has contributed to a better understanding of how to safely and efficiently provide the performance horse with sufficient nutrients, while at the same time reducing the risk of causing metabolic and behavioral disorders. Some of the most profound improvements include the use of concentrate rations containing higher fat and fiber fractions and the manufacturing of various combinations of feed ingredients that are then processed in various ways to stabilize and enhance the nutritional value of the product.

Processing of grains can have a significant effect on starch digestibility in the horse. Processed feeds, such as those that are cubed, pelleted, steamed, flaked, cracked, extruded (heated under pressure) or micronized (infra red waves heat and vibrate the starch molecule, restructuring or gelatinizing it) increase the ability of the horse to digest and absorb the starches in the feed from the small intestine. The level of increased digestibility and speed of absorption varies with the type of processing. When grains are simply rolled or crushed without heating, there is no significant improvement in digestibility. At the other end of the scale, popping grains (like popped or puffed corn) dramatically improves digestibility. Pelleted, extruded and micronized feeds fall somewhere in between.

The effect noted through popping, and to a lesser extent extruding, is probably due to the restructuring of the grain; the starch granules are altered and partly disintegrated, which makes them soluble in water and therefore more readily absorbed in the small intestine, which is the correct place for this process to take place. But, before rushing out to buy a huge corn popper or extruder to process your horse’s ration, there is a bit more to the story. Processing of grain such as popping and extruding, can have a negative effect on the horse by causing what is known as a high “glycemic response.” Glycemic response is a measure of the rise in blood glucose levels following a meal containing starch. For example, the Glycemic index (the number assigned to a feed to show how much the blood glucose levels rise) for corn has been measured by observing the increase in blood glucose concentration after the horse eats flaked corn and comparing it the glycemic response produced from the consumption of cracked corn. The greatest glycemic response and peak glucose was seen for steam flaked corn as opposed to cracked corn. Popping or extruding corn causes an even greater glycemic response. Higher peak concentrations of glucose indicate that processing such as extruding and popping improves small intestinal starch digestion, which is good in that it helps to avoid starch fermentation in the hindgut, but can be detrimental to horses that have sensitivity to changes in blood glucose such as insulin resistant horses, those with Cushing’s disease or Equine Polysaccharide Storage Myopathy. High prececal digestibility of starches is considered desirable from a digestion standpoint, but the high glycemic response seen with some types of processing such as popping and extruding has also been linked to metabolic and behavioral problems in horses sensitive to elevated blood glucose concentrations.

The level of digestibility is often offset by the added cost of processing. So if you improve digestibility by 10% but the product cost is 15% higher, than you really are losing 5% of the money paid for the feed. This is especially true of the popped grain diets.

Finally, popping and extruding has a significant effect on product density, so a scoop of pelleted or textured feeds may require as much as a scoop and a half of popped or extruded feeds to provide the same weight fed. Often this leads to underfeeding or inability or unwillingness of the horse to consume the increased volume of feed.