Though they’re not for every horse, extruded feeds offer important benefits in some circumstances.
My first experience with extruded horse feed occurred in the early 1990s. I had an aged Thoroughbred mare who maintained her weight very well on summer pasture, but lost significant weight every winter. No matter how much hay and grain I fed her, she lost all her fat over the winter. Each year she seemed to lose more, and I was concerned that one winter I would lose her. Her teeth were good but she just did not digest hay and grain well.
After extensive searching, I found a horse feed that was extruded. I could not believe the difference in my mare the first winter I gave her the extruded feed. She did not lose any weight and she loved the feed. From then on, I gave her more extruded feed and less hay during the winter, and cut the amounts back in the spring and summer when she had fresh grass to eat. She lived to be 38 years old, and died from an injury she received while playing too hard in the field.
What is extrusion?
Extrusion is a process in which feed is cooked under high pressure with high temperatures for a short time. A feed slurry is created, which is then pushed through a small die while it is still hot; the release of pressure after coming through the die causes the feed to expand. After the final product cools, it will harden and can be broken into appropriate-sized nuggets. The steam process breaks down the feed structures to make the nutrients more available. This pre-digestion process can make feeds up to 30% to 40% more digestible than standard pellets or whole grains. The final extruded feed has a very low moisture content so it will stay fresh longer.1
How extrusion changes feeds
Proteins are made up of chains of amino acids. Horses need the individual amino acids contained in the protein chains. Extrusion breaks down the protein chains into individual amino acids, making them easy for the horse to absorb. This pre-digestion may also make proteins less likely to trigger immune reactions in food-sensitive horses. Extrusion also denatures proteins, such as phytase, which can interfere with starch digestion.
Starches are converted to an easily-digested gel by the extrusion process. The expansion of starches during high pressure extrusion gives the feed a lighter, bulkier consistency, unlike the denser pellets produced from low pressure heat processing. Extrusion also makes starches water soluble, so extruded feeds easily break back down into slurry when water is added.
Simple sugars and starches in roughage, such as hay, are also made more available to the horse from the breakdown of fibrous material.
On the downside, higher heat during processing may damage the natural vitamin content of feeds, necessitating the addition of vitamin premixes. More on this later.
Benefits of extruded feeds
Native pasture is by far the best food source for the horse. Pasture grazing allows him to move about freely and pick and choose from a variety of foods. Horses will browse weeds, leaves and small branches in a native pasture setting. They are not designed to eat grains. Whole grains as well as many seeds have a hard shell and enzymes designed to prevent them from being digested when the horse consumes them.2 On the other hand, grass and browse are easy for the horse to digest and yield a wide range of nutrients to feed him and his gut bacteria.
When we bring horses off pasture and ask them to perform as athletes, we have to give them a suitable feed that provides adequate calories and is safe for them to eat. High roughage diets in a competition horse may not provide adequate nutrition and the added bulk can interfere with performance.
Pelleted feeds are less digestible than extruded feeds, and they also have several disadvantages. Horses may not chew pelleted feeds, setting the stage for choke. Less saliva is produced when pellets are consumed; without the buffering effects of saliva, stomach ulcers can become an issue.
One of the most valuable aspects of the extrusion process is its effect on starch. While horses in a natural setting do not benefit from much starch in the diet, it can be an important source of energy for hard-working horses. Much of the starch a horse ingests is not adequately digested in the small intestine, so it is not a good source of energy.
The extruded gelatinized starch is easily converted to glucose and absorbed in the small intestine. This prevents undigested starch from reaching the large intestine, where it can disrupt the balance of fiber-digesting bacteria. Horses are not able to break the beta bonds linking the monosaccharides that make up the cellulose, or insoluble, portion of fiber.3 Only the fiber-digesting bacteria located in the cecum and large intestine can break down these bonds. If too much undigested starch reaches the large intestine, the bacteria designed to digest starch will increase in numbers and fiber-digesting bacteria will decrease. This will deprive the horse of his ability to digest roughage, and can result in severe digestive upset.
Another good thing about extruded feeds is that they have very little dust. Horses that live in stalls or have to travel in trailers are constantly breathing in dust and mold particles. Many develop lung conditions such as inflammatory airway disease or equine asthma. Feeding an extruded feed along with soaked hay can help avoid lung issues and allow affected horses to breathe better.
Disadvantages of extruded feeds
Horses that are easy keepers will often gain too much weight on an easily digested extruded feed. If hay is limited to keep these horses trim, they can develop vices such as wood chewing or cribbing from excessive boredom.
Extruded feeds may also not be a good choice for horses with metabolic syndrome. These horses do not have normal carbohydrate metabolism so can react poorly to even minor amounts of sugar and starch. Although the starch in extruded feeds is pre-digested to keep it from reaching the large intestine, it is more easily absorbed into the blood from the small intestine. Unfortunately, the extrusion process needs some starch to function correctly. Metabolic horses may do better with balanced hay cubes that are guaranteed low sugar/ starch if controlled grazing on pasture is not an option.
Although extruded feeds are a better choice in many cases than pellets or grains, they are not whole foods. Any processing, especially heat, can interfere with the vitamin content of these feeds. Most vitamin premixes included in the feed are synthetic and do not offer the same benefits to the body as vitamins from whole foods.
Whole food sources of vitamins and minerals include raw fruits and vegetables such as broccoli, carrots, sweet potato, kale, cabbage, watermelon, oranges and apples. Super foods include green algae, selected seaweeds and chia seeds. Nutritional herbs and spices can also provide a variety of vitamins and minerals; they include parsley, fennel, rosemary, basil, ginger and turmeric. These are just a few great supplements to consider adding to your horse’s diet to replace nutrients lost during the extrusion processing of feeds.
Good quality hay or pasture will meet the maintenance needs of many pleasure horses, but if additional support is needed for performance or health issues, a quality extruded feed has its place. Keep in mind that extruded feeds are only as good as the ingredients used to produce them. Low quality ingredients won’t be improved by extrusion. Feeds made with non-GMO ingredients are always preferable.
Horses that do best on extruded feeds
- Old horses
- Starved equines that have lost the ability to digest
- Those with lung problems
- Young horses
- Competition horses
Summary of pros and cons
- Extruded feeds have a longer shelf life.
- More calories are available, with less energy used by the horse.
- There’s less bulk in the diet for racing and sport horses.
- Expanded, bulky extruded feeds encourage horses to eat slower and chew more, decreasing chances of choke and increasing saliva to help buffer stomach acid.
- There’s less chance of digestive upset from undigested starch.
- Extruded feeds have less dust, making them good for horses with lung issues.
- They’re great for older horses with bad teeth or those who have lost the ability to digest hay.
- Horses that have been starved will often colic when feed is ﬁrst introduced because they have lost many of the cells in the walls of their intestines; the pre-digested nature of extruded feeds works well to get these horses back on feed.
- Young horses beneﬁt from extruded feeds to support their growth, especially if they are also in training at a young age.
- The increase in digestibility of extruded feeds can lead to weight gain or boredom if roughage is limited.
- Horses with metabolic issues may not be able to handle the starch and sugar content of extruded feeds.
- Higher heat during processing may have a deleterious effect on the natural vitamins in the feed.
3Lon D. Lewis. Equine Clinical Nutrition. pp 20-21(1995).