Studies back in the early 2000s (Nadeua et al, 2000; Lybbert et al, 2007) showed that alfalfa was more beneficial for horses with ulcers (ESGD) compared to grass forages, as the high levels of calcium and magnesium it contains act as natural buffers to acidity.

Alfalfa has really deep roots – about 3 to 4 metres – and the calcium at this depth in the soil is more available for absorption. This means that alfalfa plants can take up more calcium than grass – chopped alfalfa contains between 30 and 50% more calcium than grass forages. This has real benefits for gastric health as it is one of the qualities that means alfalfa is a natural buffer to acidity in the horse’s stomach.

Early studies suggest that omeprazole is reducing calcium absorption in the horse as is seen in humans and in Swanhall et al’s (2018) study, they recommend using bio-available calcium sources in the diet to help counteract this effect.

Fibre is often referred to as structural carbohydrate which means that although it is made up of glucose just as other carbohydrates like starch are, the way in which the glucose units are linked together is different. This means that the digestive enzymes produced by the horse cannot break the links and so the horse relies on bacteria and other microorganisms to break down fibre. This releases energy that the horse can then utilise.

The digestibility of a forage affects how much energy the horse can extract from it. Digestibility is a way of describing how easy it is for the micro-organisms in the horse’s gut to break down the fibre. Indigestible elements such as lignin, make the fibre less digestible or less easy to break down. Sugar beet is very digestible and has an energy value of between 11MJ and 12MJ DE/kg whereas straw contains a large proportion of indigestible material and so has a much lower energy value at around 5 MJ/kg DE. Alfalfa is another high fibre feed that can make a significant contribution to a horse’s energy requirements. At 10MJ DE/kg it is comparable to a low energy mix but without the same levels of starch found in cereals.

Why is alfalfa so low in starch?

Like other plants, alfalfa makes sugar when photosynthesising but if it makes more sugar than it needs, it stores any surplus as starch in its roots – the part that horses don’t eat! This is in contrast to grass which stores sugar as water soluble carbohydrates such as fructan in stems and leaves.

When oil is added as a coating to alfalfa horse feeds, sugar levels are typically less than 5% but the energy is high enough to support horses in moderate to hard work. Feeds are rarely (if ever) sugar free, as even straw contains some sugar which is why we use the phrase “no added sugar” to describe our lowest sugar feeds. Combining alfalfa with oil, such as in Dengie Alfa-A Oil, produces a feed with 12.5MJ DE per kg, which is equivalent to a conditioning mix but with 10 times less starch!

FACT: Due to its low starch and sugar content, alfalfa is ideal for the laminitis prone and those with muscle problems.

The percentage of protein in a pure alfalfa feed often puts some people off feeding it but that’s because they don’t consider how much is being fed and therefore the actual amount of protein the horse is consuming. For example, the Dengie Alfa-A range contain between 12 and 14% protein. One Stubbs scoop of Alfa-A Original (400g) supplies 48 grams of protein which is about 6-8% of a 500kgs horse’s daily maintenance needs. We recommend a maximum of 3kgs (7.5 scoops) per day which very few people get anywhere near feeding which provides about 1/3 of the protein a 500kgs horse in moderate to hard work requires. This means it makes a useful but by no means excessive contribution to a horse’s protein requirements.

Whilst the amount of protein in the horse’s diet is important, so is the quality of protein supplied. By protein quality we mean amino acids, especially the essential amino acids:

• Essential amino acids are those that cannot be synthesised within the horse’s body and need to be taken in the diet.
• Lysine is just one essential amino acid and is particularly important for youngstock as it is known as the first limiting amino acid.
• A youngster can have abundant amounts of protein in the diet, but if lysine is deficient then the body is unable to synthesise other amino acids and overall this can limit growth.

Dengie’s Alfa-A range typically supply 0.7% lysine. For comparison the NRC Nutrient Requirements of Horses gives a reference value for mature cool season grass hay at 0.38% lysine. Alfalfa therefore supplies 1.8x as much lysine as average hay. Click here to learn about the benefits of feeding alfalfa to breeding and youngstock.

The mineral content of plants tends to reflect the soils they grow in. Different plant species adopt various strategies or develop abilities to source more minerals, but the minerals still must be there for the plants to access them.

Minerals are usually divided into macro- and micro- groups with the latter also being described as trace minerals. The categories distinguish minerals by the amounts needed in the diet, not their relative importance. Macro-minerals are usually measured in g/kg or a percentage, whereas micro-minerals are usually measured in mg/kg.

Another key point to note is the origin of the minerals. Those from plants are often referred to as organic sources – this is not in relation to them being chemical free, but just differentiates them from those that are from the earth; essentially those that are mined which are referred to as inorganic.

Minerals from plants – the organic form – are usually more bio-available to the horse. Inorganic sources can often be reactive and so look to stabilize themselves by latching on to other minerals which makes them more difficult to absorb. To reduce this problem you may see that manufacturers have used chelated minerals which means they are mined sources of minerals attached to other molecules to stabilize them thereby improving absorption from the gut.

Macro-minerals in alfalfa

In addition to the soil, other factors determine the mineral content in forages such as alfalfa. The level of magnesium for example, declines in alfalfa as the plant ages with the highest levels found in the first stage of development. At Dengie, we harvest the alfalfa before it matures to maximize its nutritional value. This is in contrast to the USA and some parts of Europe where the alfalfa is made into hay and so is very mature at the point of harvest.

The age of the plant also has an impact on where minerals are stored within the plant with the relative proportion increasing in leaves as the plant gets older. Obviously, this reflects the fact that as the plant matures and grows taller there are more leaves available to store the minerals but it is a key reason why we work hard to ensure the leaves are included in the finished product as it ensures horses consuming it receive the maximum nutritional benefit. The leaves are prone to shattering when they are dried which can make the product look dusty and this is why we add a liquid coating as it disperses the highly nutritious leaves evenly throughout the bag.

If horses at rest or in light work are fed plenty of forage, they are rarely short of macro-minerals. If forage intake is limited to manage body weight of good doers for example, then a shortfall can occur. The use of a supplement or balancer can help to counteract shortfalls of macro- and micro-minerals and is particularly beneficial for horses on restricted forage rations.

Some supplements contain single minerals in isolation. It is rare for a horse to require a macro-mineral in isolation and it is important to use them with care as supplementing one mineral can have a significant impact on the absorption of another.

Magnesium is often found in products marketed as calmers. Anecdotally horse owners report them working for a while but then the effect wears off. This can be due to the fact that once a deficiency or shortfall has been addressed, supplementing with more magnesium than required is unlikely to have an effect. There is no published evidence to show that supplementing above know requirements for magnesium has any impact on behaviour. Counteracting a deficiency of any nutrient is likely to be beneficial though!

FACT: Plant based sources of calcium such as alfalfa are much easier for the horse to absorb than inorganic sources such as limestone flour.

Micro-minerals in alfalfa

Micro-minerals are the most likely to be deficient in horse’s rations as UK soils are often deficient in them; examples being selenium and copper. Even horses at rest turned out 24/7 are likely to need some form of supplementation of micro-minerals to keep them in top condition. Micro-minerals have many important functions in the body including as part of the anti-oxidants that deal with the effects of exercise amongst other things.

Cobalt is a micro-mineral required by microorganisms to synthesize vitamin B12 which is important in many biochemical pathways. It is a mineral that has been used and abused by some racehorse trainers in the past who supplemented at very high levels to try and achieve a competitive advantage and so subsequently, its inclusion in feeds and supplements has been more closely monitored around the world. However, it has been found to occur naturally in plants such as alfalfa but at much lower levels than are used to try and manipulate performance. It is thought to enhance fibre digestion though and so its presence may go some way to explaining why horses do so well on alfalfa.