Feed processing to help with digestion

Depending on the processing method, the feed may look different varying from pellets to flaked grains and extruded nuggets, but is this just for aesthetic reasons or are there nutritional purposes? What does processing actually mean and why is it beneficial for my horse? All these questions will be answered in this short article, highlighting the three main processing techniques we use here at the HYGAIN equine only feed mill, its differences and various benefits.

What exactly is processing? Per se, processing refers to a series of operations performed for a specific result. In the case of grains we process or treat them by mechanical (rolling, grinding), thermal (roasting, micronizing) or thermo-mechanical (flaking, extruding) methods into dry or wet (steam flaking, pelleting, extrusion) conditions in order to improve the ingredients’ digestibility. Note; the processing of feed is not to be confused with human “processed foods” which implicate fast food, additives, preservatives, etc.

Why process grains?-The horse’s digestive system will thank you for it Factors affecting starch digestion include the level of intake, the actual ingredient (e.g. oats, barley, maize) and how the grain was processed. The processing of grains is applied to maximize the small intestine digestibility of the grain in order to reduce the risk of digestible disorders whilst increasing the nutritional value of the feed. The higher the digestibility of the grain, the more glucose and energy will be absorbed in the small intestine.

Pelleted, extruded, or micronized? In general, thermal processing (e.g. pelleting, micronizing, extruding) involves heat, which is used to “pre-digest” the grains. The heat acts in the same manner as natural digestive enzymes to break down the complex carbohydrate bonds of the grain starch (i.e. gelatinize), which increases the availability of nutrients such as glucose in the small intestine. In the pelleting process, the ingredients are ground and then steam-heated to 80-90° C for about 20 seconds. Next, the mash is pushed through a pellet die of the desired size, cooled, and dried to prevent mold growth. With forage pellets, the forage is first dehydrated before being processed. As pellets are cooled, moisture content is also reduced. The extrusion process begins with the grinding and mixing of ingredients such as grains, oil and fibre sources. The resulting mash is cooked using a combination of high temperature steam and pressure. This process involves pushing the mash through an extruder-a steel cylinder- where the mix is rotated under increasing pressure. The end product then emerges from the extrusion die, where it is cut into small cubes or nuggets, expands and “pops”, much like a kernel of corn. These cubes or nuggets are then cooled down before being bagged. Due to the higher temperatures and added pressure, gelatinization of starches is even more complete through extrusion than through pelleting. Extruded products provide the additional benefit of transforming into a soft mash when water is added, ideal for horses with poor dentition such as senior horses. During the micronizing process, the grain is heated using infrared heat until all moisture is vaporized (generally less than a minute). This ruptures the endosperm of the grain, leading the grain to become soft and pliable, causing the reconfiguration of the starch structure (gelatinization). Immediate flaking further gelatinizes the starch so as to significantly enhance the digestibility and nutritional value of the feed.

Research shows that the starch in micronized grains can be up to 95% digested in the horse's small intestine whereas the starch in whole, cracked or steam-rolled cereal grains such as barley or maize is only 20-40% digested.

Summary

• Processing = a series of operations performed for a specific result
• We process grains in order to improve the digestibility
• Horses’ digestive tracts adapted to high fibre low starch diets
• The capacity of horses’ small intestine to digest starch is limited; high levels of grain can be associated with health disorders
• Thermal processing (applying heat) “pre-digests” the grain (gelatinization), increasing the availability of nutrients in the small intestine
• Gelatinization= complex carbohydrate bonds of the grain starch are broken down
• Pelleting: feed mixed, steamed and pushed through a pelleting die
• Extrusion: feed mixed, cooked through high temperature steam and increasing pressure, and comes out of extrusion die in nugget-form
• Micronizing: grain (feed) subjected to high intensity infrared heat for under a minute which removes all moisture. The grain is further gelatinized by flaking
• Thermally-processed (pelleted, extruded, micronized) feeds have a starch digestibility up to 75% higher than the digestibility of whole grains
• The greater the digestibility of the grain, the more nutrients are available to horse and the less indigested starch will enter the hindgut, lowering the risk of health disorders
• Processing grains is important for equine gut health