Restricting Grazing

There are some food needs that just can’t be argued against: 1) Humans need popcorn plus a cola at the movies; 2) Women need chocolate anytime; 3) Horses need forage at all times. While these combinations aren’t equal in terms of supplying

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There are some food needs that just can’t be argued against: 1) Humans need popcorn plus a cola at the movies; 2) Women need chocolate anytime; 3) Horses need forage at all times. While these combinations aren’t equal in terms of supplying nutritional value, we know as humans that life certainly can be more satisfying when we have our treats. And we can even be, dare we say it, grumpy if we don’t!

The same can be said for horses and forage. Yes, some type of forage is necessary to meet the nutritional and physical needs of a horse, but there are many types of forages. However, natural forage and the act of grazing satisfies an important need, and deprivation of that grazing can lead to a grumpy horse with some nasty vices.

There are a number of reasons why it might be necessary to remove a horse from natural forage. Beware: Keeping the hay- or pasture-deprived horse happy is no easy task.

Au Natural

Although concentrates and grains with roughage added can provide a nutritionally complete and balanced diet, forages of pasture grass and/or hay should be the mainstay of the equine diet. For starters, forage addresses physiological needs that no other food source can. Explains Ann Swinker, PhD, extension horse specialist and Associate Professor of Dairy and Animal Science at Pennsylvania State University, “Horses are herbivores in nature and require roughage in small meals throughout the day in their diets. This is how their digestive systems are intended to function.

“Forage is a required source of fiber,” Swinker states. “Usable or digestible fiber is necessary as a source of energy for microorganisms in the horse’s cecum and large intestine, and it provides a source of dietary energy for the horse.”

Indigestible fiber, which is low in all non-forage feeds, is also a necessary component of the equine diet. “Indigestible fiber is required for the maintenance of normal gastrointestinal pH, motility, and function,” Swinker says.

“Indigestible fiber also helps prevent too rapid an intake of readily digested carbohydrates, which are high in cereal grains,” she adds. “Carbohydrates taken in too fast or in excess can cause diarrhea, colic, or laminitis. Therefore, a certain amount of fiber that can only be provided by feeding forage or by-products that are high in fiber (such as rice hulls) is required by the horse for normal intestinal function and by microbial organisms. Both are necessary for the horse’s health and well-being.”

Food and Behavior

Secondly, there is a behavioral component involved with hours of chewing–horses denied access to forage often develop unpleasant habits.

“We know there is a big link between stereotypical behavior–what people used to call vices–and forage intake,” says Nancy Diehl, VMD, MS, Assistant Professor of Equine Science at Pennsylvania State University. “Most literature, from research reports as well as anecdotal and nonscientific observations, notes that horses that don’t get enough forage tend to develop stereotypical behaviors, particularly cribbing. Although cribbing is extremely refractory to almost any treatment, (persistent) cribbing and other stereotypical behaviors like weaving and stall walking can be significantly reduced if you take the horses off of grain and put them on forages.” (For more on how diet affects behavior, see “Does Feeding Affect Behavior?” in the January 2002 issue of The Horse, article Quick Find #3234 at www.TheHorse.com.)

Although she cautions that her observation is subjective, Diehl notes that hot-house show horses kept on a relatively high grain/low forage ration which were stalled most of the time often appeared to lose spark and develop a very sour, sullen attitude.

It’s not a matter of an incomplete diet. “To the best of our knowledge, a complete pelleted, extruded, or textured feed is designed to meet nutritional needs in terms of protein, vitamins, minerals, and caloric intake,” says Sarah Ralston, VMD, PhD, Dipl. ACVN, Associate Professor in the Department of Animal Science at Rutgers University. “But I haven’t seen any commercial concentrate feeds that seem to be able to satisfy the apparent need for chew time. If you feed a horse a complete pelleted or extruded feed without any forage, even if you spread it across three or four feedings a day and are meeting all of his nutritional needs, the horse can look great but will still turn into a termite.

“We did studies here at Rutgers where we fed them only grain plus cubed hay,” Ralston continues. “The problem was that they could consume their entire allotment of feed in less than three hours a day. If you visit our barn here, you’ll see the effects of that. Even though they were otherwise very healthy, they seemed to need to chew. I’m not sure whether it’s driven by their gastrointestinal cues or an oral gratification issue.”

One theory for the behavioral change is that horses which eat constantly (as nature intended) maintain a higher gastric pH, thereby keeping their stomachs buffered and thus less likely to develop gastric ulcers. “By cribbing, it may be that horses are producing saliva, which buffers the stomach contents,” says Diehl. “There may be a physiological pain relief effect.”

Or, it could be that nature programmed horses to be chewing machines. Says Andrew McLean, BSc, Diploma of Education, PhD candidate, and director of the Australian Equine Behaviour Centre in Victoria, Australia, “My thoughts on this are since the horse has evolved to graze for 16-plus hours a day and a lot of brain circuitry is therefore devoted to this activity, his mental welfare is compromised when you restrict his grazing.”

Into Denial

Regardless of a horse’s physiological or psychological need to chew for long hours, sometimes circumstances necessitate that pasture or hay be limited.


Unsafe pasture–“One reason to limit exposure to pasture is if a mycotoxin is suspected to be on the pasture,” says Bonnie S. Barr, VMD, a practitioner in internal medicine at Rood and Riddle Equine Hospital in Lexington, Ky. Other kinds of grass contamination or recently applied herbicides or fertilizers can also make grass unsafe.

Overgrazing–Some pastures have difficulty supporting their herds if grazing is unrestricted. Says Barr, “Some people restrict access to their pasture if pasture is limited in order to keep the pasture green and the weeds from taking over, which may occur if the pasture is overgrazed.”

Respiratory problems–“Horses with chronic obstructive pulmonary disease, if kept indoors, are exposed to allergens present in the hay and bedding that could cause problems,” Barr says. “On the other hand, there is a summer-associated obstructive pulmonary disease that occurs as a result of exposure to specific pastures during the summer months.” That would require horses to be kept off pasture.

Allergies–“Some horses are allergic to molds, spores, or fungi on certain hays,” states Swinker. “They may also be exposed to endophytes or endotoxins in the hay.”

Pregnancy–“During their last trimester, pregnant mares should be restricted from fescue hay or grass because of endophyte fungus, unless the fescue hay or pasture is endophyte-free,” Swinker says. “Infected fescue consumed during this period may cause abortion, prolonged gestation, a thickened placenta resulting in difficult foaling, a decrease or absence of milk production, a weak foal, or maybe death of the foal.” For more on avoiding fescue toxicity, see “Fescue Field Management” in the March 2002 issue of The Horse, article Quick Find #3353 at www.TheHorse.com.

Founder or laminitis–“Horses prone to founder should be restricted from straight alfalfa,” warns Barr. “You also have to worry about lush grass and laminitis.”

Bad teeth–“If the horse does not have adequate dentition or if his teeth are really bad and he can’t chew hay, then long-stemmed hay may need to be restricted,” Ralston says. Poorly chewed hay can lead to choke or impaction colic.

Surgery–“Pre-surgery, forage should be limited to reduce fecal output in cases of rectal tear surgery or rectovaginal repair,” Barr states. “In cases of colic surgery, forages may be restricted post-surgically for a few days.”

Obesity–Some horses get fat on pasture, thus requiring reduced grazing time.

Availability/affordability–“Some people just can’t get good-quality hay,” Ralston points out, “or it is very expensive, so they restrict hay for economic reasons.” Adds Swinker, “During a drought where no long-stemmed hay is available, people must feed pellets or alternative forage sources.”

Use–“Racehorse people tend to restrict hay,” says Ralston, “because hay is a bulkier feed and adds weight to the horse. Every ounce counts in a one-mile race.”


Coping With the Crazies

Whatever the reasons, limiting pasture and hay is the easy part: Keep the horse stalled and don’t feed him hay. Or turn him out in a dry paddock, and don’t feed him hay. Reduce pasture time, or eliminate it all together. Muzzle him to keep him from ingesting sand in a sandy paddock or grass in the pasture. The hard part is dealing with the effects of forage deprivation.

Says McLean, “We are talking about a neurologically wired response that has been thwarted. It’s not a matter of soothing him, but rather one of fulfilling this hard-wired drive in some other way, like an Edinburgh Ball (a tight, heavy ball of hay that takes a long time to eat, see “Edinburgh Balls and Slow Alternatives” on page 98) or providing plenty of low-grade roughage. It is a matter of fulfilling a very basic drive that is millions of years old in its evolution. The horse does not have insight into his own instincts, like you or I do, so he cannot understand his predicament.”

To help deal with those difficulties, Ralston suggests spreading out what hay can be fed over three or four feedings, offering just a little bit at frequent intervals. “That helps relieve the boredom,” she says.

Hay substitutes might also help. “Use the closest thing to forage that you can,” recommends Ralston. “Chopped hay products, hay cubes, and beet pulp do a good job of providing some form of fiber to the horse’s gastrointestinal tract. However, they’re so easily digested and consumed that you are going to potentially run into some adverse effects, such as wood chewing and, in some horses, choke.”

Gas colic due to bypassing digestion in the small intestine, resulting in over-fermentation in the large colon and cecum, is another possible side effect, Barr notes. She cautions that beet pulp should not be fed as a sole source of nutrition because it does not contain the proper balance of nutrients. Wheat bran, which is also a good source of fiber, should not be used for long periods or in large quantities because bran is extremely high in phosphorus and will cause calcium/phosphorus imbalances. (An imbalance in the calcium/phosphorus ratio is likely and will adversely affect bone strength, Ralston emphasizes.)

An option for horses with chronic obstructive pulmonary disease is hypoallergenic hay. “I know several people who have their horses on it because of COPD and it seems to work,” says Barr.

Horses on a forage-restricted diet might benefit from turn-out in a paddock and exercise. “Normal movement and exercise is needed for normal intestinal and digestive function,” says Swinker. Ditto for physical and mental stimulation. Movement and exercise is needed for the horse to maintain its health and sanity. “Keep horses on a schedule,” Swinker says. “Do not lay off riding, exercise, or work.”

Toys generally do not offer long-term stimulation. “Toys don’t really alleviate the problem,” says Diehl. “They’re like children’s Christmas toys–most of the time they get forgotten. Toys don’t replace forage. Exercise doesn’t really replace forage, either. Nothing really replaces forage.”

The bottom line is that non-forage diets should only be fed under the direction of a veterinarian and due to a major health problem, Swinker says. “Each class of horse requires a certain amount of fiber and roughage in their diets. Some horses will reject quite palatable feed and start eating poor hay or bedding.”

If you and your horse are in a situation where your horse has to go the non-forage route, per your veterinarian’s approval try your best to satisfy him with substitutes, spreading out feeding times, providing products that take a long time to eat, and utilizing physical exercise to help keep him occupied. If your horse gets grumpy or starts displaying stereotypical behaviors, try to remain patient and understanding, grit your teeth, and reach for a chocolate bar

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Written by:

Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She’s schooled in hunt seat, dressage, and Western pleasure.

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