Competing on a fibre-only diet

It is widely acknowledged that the nutritional requirements of sports horses – show jumpers, dressage horses and eventers – cannot be met by high-bulk, low-energy forage, such as hay, alone. As a result many owners successfully feed their performance horses a diet that includes energy-dense feedstuffs such as cereal grains, which they know will meet the horse’s needs.

However, horses evolved to eat a fibre diet and their intestinal system is designed to process large amounts of low-quality forage, ingested on an almost continual basis. BHS Intermediate Instructor, lecturer and course coordinator for the new MSc Equine Science programme at the Royal (Dick) School of Veterinary Studies, University of Edinburgh, Dr Jo-Anne Murray, has been undertaking research into whether it is possible to keep a performance horse at the top of his game by feeding a fibre-only diet.

“Horses’ intestinal systems have remained largely unmodified since they have been bred for roles such as racing, endurance and eventing, which often involve extensive periods of confinement and high-starch diets,” Jo-Anne says.

“They are often fed a diet that includes substantial, single meals of cereal grains, and supplementing with grain has often overshadowed the forage contribution of the horse’s diet. I have also found that the forage component of a performance horse’s diet is often less than the recommended level required to maintain gut health and integrity.”

According to Jo-Anne, while forage should form the basis of all rations, the low-quality, conserved forages, such as grass hay, fed in the UK do not meet the energy demands of working horses and ponies when fed alone.

She believes that highly digestible, quality fibre such as alfalfa fits the nutritional bill. Alfalfa is a member of the legume family, a group that includes pulses, peas, beans and lentils. “Legumes have a higher protein and mineral content and accumulate low amounts of starch instead of fructans [storage carbohydrates that can trigger laminitis],” Jo-Anne says.

Many owners are already familiar with the benefits of alfalfa – it is often used to provide a consistent source of additional fibre, conserved using high-temperature dehydration. It is added to equine diets due to its high nutritional value and ability to improve mastication (chewing) of hard feed, but is often overlooked as an energy source.

In the UK, grass is commonly ensiled (fermented in the absence of oxygen) and fed to horses as haylage, as it has a higher nutritional value than grass hay. However, Jo-Anne says no other scientific studies have evaluated the use of alfalfa haylage in horses’ diets, but her research suggests that it could provide even more nutrients than grass haylage, offering an additional 1.4MJ (megajoules) of digestible energy per kg of dry matter.

If fibre is the way forward, then do low-starch, fibre-based coarse mixes provide the perfect compromise for the problem of high-starch diets? A diet high in starch can be detrimental to a horse’s digestion, as any undigested starch can ferment horse’s hindgut, causing a reduction in the pH level and subsequent undesirable high acidity.

“Our results indicate that a greater amount of starch reaches the large intestine of ponies fed a high-starch cereal mix than those fed a fibre-mix feed,” says Jo-Anne. “Therefore, fibre mixes are definitely preferable to a high-cereal diet and meet the energy demands of the performance horse while maintaining gut health.”

When HT (high-temperature-dried) alfalfa and sugar beet pulp are fed together, they can provide enough energy for the horse in intense work, according to Jo-Anne. “These feedstuffs are also rapidly digested, therefore reducing the gut weight often found with grass hay,” she explains.

She adds: “The addition of sugar beet pulp to alfalfa increases the digestible energy content of the ration even further.” When Jo-Anne added a specific ratio of sugar beet pulp to HT alfalfa, an increase of around 0.6MJ of digestible energy per kg of dry matter was seen. When sugar beet was added to alfalfa silage, the increase was around 0.5MJ.

By including sugar beet pulp and alfalfa in the horse’s diet, you are increasing the energy content of the ration, thus further reducing the need for supplementary cereal grains, Jo-Anne says. “However, further studies are required to determine the performance of horses in intense work when fed these types of diet,” she adds.

Jo-Anne’s research shows that conserved alfalfa can provide all a horse’s digestible energy requirements for moderate work – for example, if he is ridden more than four times a week and competes in one-day events – and that the addition of sugar beet, fed at an additional 20-30 per cent of the total ration, can meet the nutritional requirements of the horse in intense work.

Supporters of fibre-only diets include dressage rider Hannah Esberger-Shepherd, who has has been feeding her dressage horses a low-cereal diet for nine years, and endurance rider Rachel Dewar.

“When I began the regime in 1995, my horse, Fernando, who went on to be on the Olympic squad, was a very ‘hot’ horse,” says Hannah. “I found that feeding a base of HT alfalfa made a considerable difference to his nervous energy.

“All my horses have stayed on my ‘bible’ feed regime ever since, consisting of a base feed of HT alfalfa with the optional addition of alfalfa fibre-mix products containing ingredients such as linseed, soya and some cereal.”

Rachel Dewar is not surprised by the results of Jo-Anne’s research, having experienced fist hand the benefits of feeding alfalfa with sugar beet.

“The horse that took me to a Gold Thistle (a 50-mile endurance ride) was a good doer prone to weight gain,” she explains. “I read a lot about the requirements for endurance horses on long rides in the heat, and spoke to various feed manufacturers. I didn’t want a cereal-based diet with the possibility of excess starch making the horse too lively, or causing problems such as laminitis or tying up, and therefore chose an HT alfalfa feed, as I knew the nutritional content was consistent.

“I also introduced my horse to sugar beet to get him to drink on longer rides and I found that the residue of soaked beet made an excellent mix with the alfalfa. He did well on this combination and it didn’t make him too fresh.”

This feeding feature was first published in HORSE magazine (November ’04)