The BENEFITS of feeding Lucerne

Lucerne is a very nutritious feed and source of fibre. It contains about 18% high-quality protein which provides good levels of all the essential amino acids for horses, including lysine, which can be low in many feeds, including grains. It is high in digestible fibre, including pectin, which provides sustained energy (it is converted to glucose, glycogen and fat in horses’ livers) and is very good for digestive health because it promotes beneficial gut microflora. Lucerne is readily available, very palatable, and highly digestible.

Is Lucerne high in CALCIUM?

It is high in calcium which is in a highly bio-available form, providing around 15grams per kilo, which is essential for health (bones, joints, hooves, nervous system, metabolism) and is useful for balancing concentrates which are high in phosphorus, eg grains, copra, soy, lupins, bran (both wheat and rice bran), pollard and millrun. Adult horses need roughly twice as much calcium as phosphorus in their diet and young growing horses need about 1.5 to 2 times as much calcium as phosphate. It is also very useful for providing calcium for horses grazing on high oxalate pasture (eg Setaria, Buffel, Kikuyu. (Oxalates bind with calcium in horses’ GI tracts and cause calcium deficiency). Most equine nutritionists also recommend that magnesium should also be supplemented in the correct ratio to the calcium in the Lucerne.

Is Lucerne high in SUGAR?

Lucerne is relatively low in sugar and starch, containing about half the amount of cereal hay (oaten, barley and wheaten) so it doesn’t cause large insulin spikes and blood sugar level fluctuations and is very useful as a component of feed for horses with laminitis or metabolic issues such as insulin resistance. (It isn’t suitable for horses with HYPP though, because it is too high in potassium. Also, some horses with Cushings do not tolerate the protein in lucerne well.)

Lucerne's effect on ULCERS

Lucerne is very good for buffering stomach acid and helps to prevent ulcers due to its high pectin content (and other types of fibre) and minerals (eg calcium and magnesium) which are alkaline and help neutralise stomach acid. (It is also a good idea to feed a small amount of Lucerne chaff or hay to horses with ulcers before riding them to help buffer the stomach acid.) It provides good levels of chlorophyll which contains antioxidants, which help prevent oxidative damage and helps balance the body’s PH, and is therefore healthy for horses. Unlike some other feeds, Lucerne contains no known anti-nutrients like oxalates, phytates, cyanogenic glycosides, goitrogens, enzyme inhibitors etc. It is also relatively low in phytoestrogens, unlike other legumes, eg soy and clover.

The CONCERNS when feeding Lucerne

Lucerne provides about 18% protein (and can be even higher than that), which is high for horses. Excessive protein intake should be avoided in horses in work because it increases horses’ requirements for water (necessary to excrete ammonia, the by-product of protein metabolism), urea levels increase in the blood leading to greater urea excretion into the gut, which may increase the risk of intestinal disturbances such as enterotoxaemia, and the level of ammonia in the blood increases, causing a number of problems such as nerve irritability and disturbances in carbohydrate metabolism. (See Kentucky Equine Research article “Protein requirements and a review” by Joe D Pagan). Providing a biscuit or two of lucerne per day is a very good way to improve the amino acid profile and therefore the protein level of the diet, but feeding lucerne as the main or only source of roughage may cause problems due to excessive amounts of protein.

Lucerne and CALCIUM BALANCE

Horses need a ratio of calcium to magnesium, and also calcium to phosphorus of 2 to 1. (For growing horses, as stated above, the ratio should be 1.5 to 2 to 1 calcium to phosphate.) Lucerne provides a ratio of calcium to phosphorus and magnesium of around 5 to 1.This means that if Lucerne is fed as the main or only source of roughage, magnesium and phosphorus will need to be provided from other feed (including pasture) and/or supplements to balance the ratios. Lucerne (like most other forages and feeds) is also high in iron and low in zinc and copper. It is also low in sodium (and in Australia, most likely low in iodine as well).

Low indigestible Fibre and Sensitivity

Lucerne is higher than many other roughage sources of digestible fibre which is very good providing cool sustained energy and promoting beneficial gut microflora, but it is lower in indigestible fibre, important for gut motility and removing waste from the digestive tract regularly, so second grade more stalky Lucerne is usually better for horses than prime Lucerne, or if prime lucerne is fed it should be fed with either grass or cereal hay to provide more indigestible fibre. Some horses are known to be sensitive or allergic to Lucerne (and some other legumes eg. soy).

FIBRE IN HORSES DIETS: WHY IT IS SO MUCH MORE THAN JUST A FILLER!

In this article:

Fibre and the digestive system in horses
Why is FIBRE so important?
Converting fermentable components in the FIBRE
Fibre is NOT just a FILLER
The BENEFITS of FIBRE in horse’s diet

Horses are “trickle feeders” (meaning they are designed to ingest relatively small amounts of food gradually over long periods each day) and “hindgut fermenters” (which means that the fibrous component of their diet is fermented in their large intestine). Their entire digestive system is designed to process fibrous plant matter almost constantly.

FIBRE AND DIGESTIVE SYSTEM IN HORSES

Horses left to their own devices in paddocks and in the wild spend about sixteen hours per day grazing and ingest a minimum of 1% of their own body weight in fibre (comprised mainly of pectin, cellulose, hemicellulose and lignin) each day. It translates to about 1.5 to 2.5% (or more in some cases) of their own weight per day in pasture and other fibrous plants.

Pasture and other fibrous plants provide other nutrients as well as fibre, eg protein, simple carbohydrates, starch, fat, vitamins and minerals.

Horses have small stomachs relative to their size but have large hindguts acting as a fermenting vat where the fibrous plant matter is digested and absorbed.

When a horse grazes or eats a feed most of the digestion of protein, carbohydrates (sugar and starch) fat and vitamins and minerals occurs in the small intestine, but all the fibre is fermented/digested in the large intestine.

WHY IS FIBRE SO IMPORTANT?

All mammals, including horses, are not able to digest fibre at all, and yet fibre is crucially important as a source of nutrition for horses. So how is it that fibre is such an important component of horses’ diets if they are unable to digest it?

The answer is that horses and all other mammals rely on billions upon billions of health-giving beneficial microflora (tiny single-celled micro-organisms) that live and breed in their hindgut to ferment the cellulose, hemicellulose and pectin which are components of fibre.

Only lignin (the component of fibre that makes some grasses and plants tough and stalky) is not able to be fermented by gut microflora. Therefore has no nutritional value, but it still has a role in toning the muscles surrounding the intestines and helping to bulk up the ingesta moving through and ‘sweeping out’ contaminants like sand from horses’ GI tracts.

Horse nutritionists teach that one of the best ways to prevent or treat sand in the gut in horses is to feed ad lib grass hay.

CONVERTING FERMENTABLE COMPONENTS IN THE FIBRE

The beneficial microflora in horses’ large intestines convert the digestible/fermentable components in the fibre to volatile fatty acids (some of which the ‘good bugs’ consume as a source of food) and the horse absorbs the rest of the VFAs through the hindgut lining where in turn they are converted to:

glucose (the form of energy required by all organs and cells),
glycogen (glucose stored in muscles),
fat.

This is the reason why some feeds, although they are low in sugar and starch, are high in calories/energy; it is because they are very good sources of digestible fibre.

Beet pulp, for example, provides roughly the same calories as oats, but in the form of fermentable fibre (for slow release sustained energy), rather than sugar and starch from grain (which is useful as a source of quick release energy for horses in hard or fast work, but if fed to excess can cause blood sugar level fluctuations, insulin spikes and hindgut issues for horses).

FIBRE IS NOT JUST A FILLER

Many people think that fibre is just a ‘filler’ or is necessary to ‘bulk up’ a hard feed or keep a horse ‘busy’ while the horse is confined, but that it has little or no nutritional value.

However, nothing could be further from the truth. Fibre (except for the lignin component already mentioned) is highly nutritious and is a very valuable source of cool, slow release sustained energy for all horses, for maintenance, growth, reproduction and performance.

THE BENEFITS OF FIBRE IN HORSE'S DIET

As well as being a very valuable source of slow release energy in horses’ diets, fibre has other benefits for horses, including its ability to:

Slow down the rate of movement of feed through the digestive tract allowing the nutrients to be digested and absorbed more efficiently.

Act as food for beneficial gut microflora (fermentable fibre is prebiotic) so they can breed and proliferate, and this boosts digestive function and the absorption of nutrients as well as having beneficial effects on the immune system. By promoting beneficial microflora, a high fibre diet also discourages the overgrowth of pathogenic (disease causing) microflora that can lead to digestive disturbances including colic, inflamed intestinal lining, hindgut and associated behavioural issues, laminitis etc.
Stimulate the production of more saliva than other lower fibre feed types and this helps buffer stomach acid and reduces the likelihood of ulcers. Horses produce stomach acid constantly whether they are eating or not, and ad lib access to pasture or other fibrous feed (eg hay, lupin hulls, beet pulp etc) is very helpful in buffering the stomach acid, and stimulates the production of saliva which contains sodium bicarbonate, which is a natural acid neutraliser.
Provide calories/energy in a slow release sustained form that does not cause insulin spikes and blood sugar level fluctuations that can be caused by feeds high in sugar and starch (eg grain and grain by-products).
Reduce the likelihood of stereotypical behaviours like crib-biting and windsucking that occur in horses who are stressed from being confined or from high energy/low fibre diets that do not simulate horses’ normal patterns of grazing on forage. In situations where horses don’t have 24/7 access to pasture, they should always be provided with ad lib hay to help prevent any digestive and behavioural issues.
Encourage horses to drink more water (plus water can be added to feeds containing beet pulp, lupin or soy hulls etc) and this provides a reservoir of water and electrolytes in the hindgut which helps prevent dehydration and electrolyte depletion in horses during sustained bouts of exercise. This is particularly useful for horses involved in the sport of endurance.

Written by Elizabeth Funnell
Equine Nutrition Educator

Sub-editor Bryan Meggitt (BMedSc. PGCrtMedSc.)
Senior Scientist and Co-founder of CEN Horse Nutrition

References

Nutrient Requirements of Horses – sixth revised edition National Research Council
Super Fibres – Kentucky Equine Nutrition Equinews publication Jan, 2002
Fibre for performance horses: A Review – Journal of Equine Veterinary Science Richardson, K and Murray, J. A.M.D. 46, pp31-39