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Nutritional Management Of Horses: Is Psyllium A Player?

Today, there are a plethora of nutritional products on the market compared. This growth in product offerings has also been coupled with confusion with the information that circulates on “how to feed horses”. One of the confusions includes the use of products to prevent colic. Since nutritional management has always been my focus, the information that follows should help with how one makes those nutritional management judgments concerning products that promote a laxative effect.

The fundamental objective in feeding bulk laxatives to any animal (including humans) is to force the gastrointestinal tract to contract differently and “to move” with more vigor. The gut is a muscle and with contractions the contents of the gut will move through the pipeline. As the gut contracts with more vigor then the gut content will move through the gut at a faster rate. The standard for scientists in which the movement of the gut’s content is measured is referred to as the rate of passage (ROP) or transit time (TT). Remember that most adult horses’ diets consist primarily of forages, that is, hay or pasture. These feedstuffs contribute the fiber or bulk of the diet. Fiber sources not only provide sources of energy and nutrients but also contribute to gut integrity. Gut integrity requires a stable, healthy microbial population that resides in the gut. The emphasis this nutritionist places on fiber intake via forages can be found in Dr. Bray’s Corner Fact Sheet section title, Feeding Guidelines for Horses.

So if a horse is fed a diet high in fiber, is there a need for a psyllium product to add bulk or to provide a laxative-effect? The apparent recommended feeding amount of various psyllium products approximates 2 – 4 ounces per day. There are different regimes promoted that include daily feeding to feeding for 5 - 7 days per month. Keep in mind that fiber is a fundamental component of the diet that influences ROP. Four (4) ounces of psyllium provides less fiber than one cup of wheat bran. For comparison if an 1100 lb horse is fed Bermuda grass hay at 1.5% of body weight then this amount of hay provides 350 times more crude fiber than one cup of wheat bran and 420 times more fiber than 4 oz of psyllium. Thus, the amount of fiber provided by 4 ounces of psyllium and one cup of wheat bran is insignificant relative to contributing bulk to the diet in the form of fiber.

The claim that circulates in the horse industry is that psyllium “picks up sand” in the gut. Another recollection of psyllium lore was correlating the action of psyllium to “a wad of gum rolling-along inside a tube with sand sticking to the wad”. If you think about these assertions, hopefully you will conclude that psyllium is perhaps provided more credit than it deserves. Remember, psyllium is a feedstuff and is exposed to enzymatic and microbial digestion just like every other feedstuff in the diet. The inference that psyllium has the ability to selectively “pick-up sand” and ignore all other digesta particles in the gut lacks sound reasoning. Psyllium does provide laxative-like properties but are the amounts recommended adequate? I do not believe so and perhaps if fed daily at sufficient quantities may cause the gut to contract with more vigor, but then those amounts would be costly.

So, what are sufficient amounts of fiber? Frequently and misleading, the known benefits of human nutrition have been used to justify a product’s application with horses and other companion animals. Humans however are not non-ruminant herbivores and do not have the hindgut capacity, the same number of compartments, nor the gut length of horses, thereby they have different dietary requirements. Recommended intakes of fiber for humans are 25 – 35 g/d, although the average fiber intake for most people is less than half of that recommendation. Compare these numbers to this nutritionist’s fiber recommendation for an 1100 lb adult horse of 2000 g crude fiber or 2300 g ADF per day. Now there is a difference in how fiber is measured. Humans use total dietary fiber (TDF) while with horses acid detergent fiber (ADF) or crude fiber (CF) is used. TDF is more inclusive but this difference in measurements does not interfere with the principle that the requirements are totally different quantitatively.

Granted, fiber intakes has not been clearly established for horses, BUT the suggested fiber requirements are somewhat implied by the recommended forage intakes. For horses, my recommendation is 1.8 g of crude fiber or 2.1 g ADF for every lb of body weight. This empirical determination has evolved from experiences and industry research and thus outlined in the forage guidelines in the Fact Sheet section title, Feeding Guidelines for Horses. Having forage analyzed and one mathematically determining the fiber requirement is not practical of course, but there are standards we know about forages and its composition. This is why one of my recommendations is feeding a minimum of 1.4 – 1.5% of the adult horse’s body weight in hay for horses that do not have pasture.

The recommendations for feeding psyllium for colicky horses are frequently accompanied by several other recommendations. As you review the Nutritional Management recommendations below, ponder what has more influence on the horse’s gut, the nutritional management recommendation of the diet or feeding psyllium.

Nutritional Management Recommendations

  • Recommendation: Feed more hay
    What Does It Do?An increase in hay intake will increase the water intake, thus more fiber and more gut fluids. Both effective in influencing the contraction of the gut.
  • Recommendation: Feed the hay portion of the diet more than two times per day
    What Does It Do? - Feeding roughage more than the traditional two times per day will reduce the hay spread along the ground and loss. More feedings will influence a consistency in gut contraction.
  • Recommendation: Feed hay in elevated hay-racks over a feed trough
    What Does It Do? Most likely this will reduce the horse browsing the ground for hay and reduce hay loss spread over the ground.
  • Recommendation: Place rubber mats under the hay-rack or feed on rubber mats
    What Does It Do? Most likely will reduce the opportunity for ingesting sand while browsing the ground for loose hay. Of course you will need to make it a daily routine to sweep the rubber mats.
  • Recommendation: Exercise the horse
    What Does It Do?Horses that exercise will drink more water. Water is also a lubricant of the gut. An increase in water intake will increase the ROP.

Colic is a serious ailment and usually horse owners will spend more time with their horses that have been sick, including frequently checking on them and exercising them more frequently. So what does exercise do for the horse? Exercise will increase water intake (water provides lubrication) and will increase the contraction of the gut, regardless of the level or type of exercise. Exercise and water are perhaps the two best natural and cheapest nutritional management components that can contribute to the “laxative effect".

Horses are browsers. Hay is processed in an imperfect system in which foreign objects and particles are picked up during the cultivating and baling processes of hay. Efforts to eliminate the harmful effects of foreign materials feared by horse owners, including sand, by feeding laxatives are not practical.

Another question evolves from those colicky horses that were treated clinically. Clinical treatments of colic may include 1.0 lb of psyllium mix with water administered via naso-gastric tube. The benefits of this treatment are evident. Not only does the treatment involve a large quantity of psyllium but also includes a large volume of water mixed with the psyllium and the mixture is administered directly into the stomach.

Mineral oil may also be part of the mixture to provide lubrication. Keep in mind that the gut of a colicky horse has been compromised by the “first-class belly ache” and horses have usually been off feed and water. Therefore, the gut content is less than normal and gut activity has been compromised. One can reason how horse owners have extrapolated the clinical benefits of psyllium to daily use. Popular press articles have thus perpetuated a variety of dose and frequency recommendations, even as high as 1.0 lb of psyllium for a 1000 lb horse.

There are fiber-containing feedstuffs, called “soluble fiber” sources that can partially be broken down by microbes that reside in the gut including the lower end of the small intestine. This pre-cecal digestion property of “soluble fiber” sources contributes to its ability to encourage gut motility and theses feedstuffs can be fed economically at much larger quantities. Beet pulp and soybean hulls are common sources of soluble fiber and are major ingredients in the Integrity product line. Every Integrity product contains one or both of these fiber sources as a major ingredient.

So, what works to maintain a healthy gut? Consistency in feeding protocol, feed daily adequate levels of forage, frequent feedings of the daily forage allotment, feeding balance formulas high in beet pulp and soy hulls, and common sense relative to nutritional management, exercise and water.