THE LUCERNE DEBATE
Lucerne hay is made from the Lucerne plant, a temperate perennial plant that originated in the Middle East. The Lucerne plant is a leguminous plant species, meaning that it belongs to the legume family of plants, that produce seed pods and have nodules on their roots that are capable of taking inert nitrogen from the atmosphere and converting it to organic nitrogenous compounds that are available to the plant.
Lucerne hay, when it is produced and stored correctly is commonly green in colour and is best when it contains a high percentage of leaf material.
The Nutrient Profile of Lucerne Hay
Lucerne hay is a reasonably high amino acid forage. Lucerne also contains high concentrations of Calcium and Magnesium and, when fresh, also vitamins A and E.
Lucerne is however typically low in Phosphorous and depending on where it was geographically grown, contains varying concentrations of other macro and micro minerals. Below shows an abbreviated nutrient profile of early bloom Lucerne hay in comparison to grass hay and oaten chaff.
Variation in Quality
The main factor when attempting to understand feeds and their analysis is that most are grown in highly fertilised ground and then sprayed religiously with toxic pesticides and fungicides etc. This has a huge bearing on the health of both our animals and us. Other studies shows that Lucerne grown in alkaline soils can have magnesium levels of up to seven times as high as the normal levels, again emphasising the problems and risks involved with variations in composition. This is why I am very respectful when it comes to feeding isolate chemicals. Foods contain much of the chemistry needed in our horses diet; the problem is the toxic environments, which the food is grown in.
Imbalance in the Phosphorous to Calcium Ratio.
Most people are aware that Calcium is an essential nutrient and mineral in the development of a strong and healthy bone structure. The increased requirement for dietary Calcium in the nutrition of pregnant mares, young and growing horses is well known. It is not so commonly known however that the ratio of Calcium to Phosphorus in the diet is as crucial as the inclusion of Calcium itself. It is also important to understand that certain foodstuffs contain Calcium and Phosphorus in forms that are unavailable to the horse. This is because certain chemicals in feeds such as oxalates and phytates bind Calcium so that the horse cannot digest it.
Calcium is not only involved in structural components of the body, but is also extremely important in its dissolved form for processes such as muscle contraction, blood clotting and as a messenger molecule in cells within the body. So important is its role that the body keeps the amount of dissolved Calcium between strictly controlled levels through a process known as homeostasis.
The body regulates the dissolved Calcium levels by drawing on Calcium in the bones in times of need, and by ensuring that excess Calcium is deposited in the bones in times of good supply. A hormone called the parathyroid hormone regulates this homeostatic process. Parathyroid hormone in conjunction with vitamin D help to keep the balance of Calcium to Phosphorus in the bones in a ratio of around 2:1.
Why is Lucerne’s high Calcium content a disadvantage?
When horses are fed Lucerne as the sole roughage, Calcium is supplied well in excess of their daily requirements. For example, 5kg of Lucerne supplies approximately 70g of Calcium, which is more than twice the daily requirements of a 400kg horse at hard work. In response to this large and continuous supply of Calcium in the diet, the body will adjust its calcium-regulating hormone levels accordingly – the Calcitonin responsible for storing Calcium will increase, and levels of parathyroid hormone will decrease. From the body’s point of view, there is no need to maintain high levels of a Calcium-mobilising hormone when excess Calcium is consistently provided in the diet.
This supply and demand concept can become a problem during strenuous events. Since Calcium is required in large amounts for muscular contractions, plasma Calcium levels gradually fall as the duration and intensity of exercise increases. In response to falling plasma Calcium levels, the body calls upon parathyroid hormones to mobilise more Calcium from its storage depots in the bone. However, because the body has become accustomed to having excess Calcium available from the diet, it can happen that the concentration of parathyroid hormones is too low to adequately supply stored Calcium quickly enough to meet the sudden high demand. In other words, there are not enough workers available at a moment’s notice to move Calcium from storage into circulation. As a result, plasma Calcium levels may continue to fall, increasing the likelihood of metabolic problems such as 'Tying Up.'
Other Mineral Deficiencies.
It also must be kept in mind that Lucerne hay is not a complete feed and will more often than not contain insufficient concentrations of trace minerals, in particular Copper and Zinc, to support sound musculoskeletal development.
To which horses can Lucerne be fed?
Lucerne may safely be fed to all classes of horses, however, due to its high protein and relatively high energy characteristics, it must be fed to horses in controlled quantities to prevent problems that may be caused by excess energy and protein in the diet. The suitability of Lucerne for different classes of horses is discussed in more detail below:
Growing horses
When feeding Lucerne to growing horses, the amount fed should not exceed the growing horse’s energy requirements. Growing horses fed energy in excess of their requirements have a much higher chance of suffering from developmental orthopaedic diseases including osteochondritis dissecans (OCD). Note that High Protein (converted to amino acids) levels are not indicated in the cause of OCD, and amino acids are vital for all growing animals.
Feeding protein in excess of the growing horse’s protein requirements does not appear to be detrimental and cause issues such as OCD as the protein can be utilised as a source of energy. Moderation seems to be the key, and again, a mixture of other hay/chaffs and Lucerne (+/- 3:1) will keep you on the safe side. I personally like 25% Lucerne.
Pregnant and Lactating Mares
When feeding the pregnant mare Lucerne hay, care must be taken not to exceed her energy requirements which will then cause her to become overweight. Conversely, Lucerne hay alone will not be capable of meeting the early lactation mare’s energy requirements and her Phosphorous and trace mineral requirements will also not be met by a diet based mainly on Lucerne hay. Depending on pasture conditions, mares need to be fed a good quality concentrate to maintain body condition throughout lactation.
Performance Horses in work or training.
With performance horses, as with growing horses and pregnant mares, Lucerne must be fed in moderation. Unlike the above classes of animals, excess protein in the diet of working horses, particularly those that are stabled, can be detrimental to their health and performance.
Excess protein intake will increase urinary ammonia production, which may in turn cause respiratory problems for horses confined to the stable and can contribute to dehydration due to water loss through increased urine production and excretion. Excess protein also increases the amount of heat produced during the digestion and utilisation of feedstuffs. A diet which contains protein in excess of the horse’s requirement can increase the horse’s water and electrolyte loss through sweating and can contribute to hyperthermia, and decreased performance or endurance capacity.
Does excess protein directly affect performance? Almost certainly yes. Although there are no scientific studies which specifically examine the effects of an all-Lucerne diet, there is significant evidence that diets with excess Protein are detrimental to endurance-type exercise. Dr. Sarah Ralston, PhD, DVM, (dACVN) has observed in both endurance and three-day event horses that as protein content of the ration increased, so did metabolic failure. Michael Glade (PhD), in observing feeding practices and racing performance in Australian Thoroughbreds, observed that horses ran slower as the protein content of the ration increased over requirements. And finally, many horse owners report that grouchy, temperamental, “hot” horses become calmer, steadier and more consistent performers when excessive Protein is removed from the ration.
It is important to understand that these effects are not as a direct result of feeding Lucerne, but can result from feeding too much Lucerne. They can be avoided by ensuring that a horse’s protein requirement is adequately met but not unnecessarily exceeded. It is important to keep in mind here the big variation existing between Lucerne batches and again this explains why it is advisable to use a grass or cereal hay in conjunction with Lucerne hay.
Spelling Horses
Lucerne hay can play a role in the spelling or non working horse’s diet, and will help to supply these horses with good quality protein and calcium in their diet. However, due to its high energy content in comparison to other forages, Lucerne hay is generally not suitable as the sole source of roughage for this class of horse as it can encourage excess weight gain.
Ponies
Ponies may be safely fed Lucerne, but I reiterate, it must be fed in moderation because it can easily lead to excessive weight gain in ponies, particularly those that are 'good doers'.
Lucerne is particularly useful in the diet of aged ponies. As horses and ponies age, they lose some of their ability to digest fibre and protein. Feeding them an easily digested fibre and high quality protein source in the form of Lucerne will allow them to maintain bodyweight, particularly during winter. Moderation again, however, is important.
Horses with Ulcers
It is commonly known, accepted, and promoted in the equine nutrition and veterinary world that the capacity of feeds and forages to counteract changes in gastric pH (stomach acid) plays an important role in the prevention of gastric ulcers in horses. This ability to resist changes in pH is called buffering capacity. Lucerne has been shown in multiple studies to be effective in reducing the severity of ulcers in horses by providing superior buffering capacity compared to other forages.
Lucerne provides greater buffering capacity compared to grass forages for several reasons. First, Lucerne contains higher levels of protein and calcium, both of which buffer gastric acid. Also, Lucerne cell wall contains certain indigestible compounds such as lignin that gives it a greater buffering capacity than grasses.
It is recommended that horses are fed a small amount of Lucerne before a workout to put a fibre mat over the acidic stomach contents and reduce acid splash, as well as providing Lucerne with each meal to provide an increase in buffering capacity.
Considerations
The Lucerne plant’s stage of maturity when cut, its weathering and handling during harvest/drying and the length of time it is stored prior to being fed will all affect Lucerne hay’s energy, protein, vitamin and mineral content. Thus, when including Lucerne hay in a horse’s diet, it is important to assess the Lucerne’s quality, before feeding it. Care should be taken to ensure that the hay does not contain mould or dust which will make the hay unpalatable and may contain fungal spores capable of causing heaves, coughing and bleeders or mycotoxins which could result in abortion or death.
Poor quality Lucerne hay is typified by:
low leaf content
high levels of foreign matter
large variations in moisture content
high leaf loss
poor shelf life
dustiness
musty smell
Making quality hay is dependent on producing Lucerne of the correct moisture content at baling time. If it is too dry, the hay will be stalky and dusty with low leaf content which means low food value and poor value for money. If too wet, however, the hay will heat during storage and become mouldy, shortening the storage life. Mouldy hay can also induce colic in horses.
Take into consideration that a heavy bale is not necessarily a quality bale, as the weight can vary widely with moisture content, and could be a sign that the Lucerne was too moist when baled.
Conclusion
Lucerne is a valuable feedstuff for horses and is capable of providing them with energy, high quality protein and often much needed lysine and calcium. Lucerne hay has to be used correctly in the diet however, to realise its full benefits.
Typical problems due to excess energy and protein are very real possibilities when Lucerne hay is not fed in moderation. These problems are not, however, as a direct result of feeding Lucerne hay, but rather, as a result of providing too much energy and/or protein in the total diet. Making slight alterations to your horses energy and/or protein levels within his concentrates (ie reducing their amount) will leave room for additional energy and/or protein from the Lucerne hay, avoiding ”hotness” or protein excess.
Another definite risk involved with feeding too much Lucerne is the Calcium to Phosphorous imbalance. Using grass hays in conjunction with Lucerne hay to fulfil the horse’s roughage requirement will help to avoid some of the problems associated with feeding excess Lucerne hay and will additionally, in most instances, reduce costs.
Choosing quality Lucerne and feeding in moderation is key to utilising this extremely valuable forage.
Zinc is essential in bone, cartilage and hoof formation. Deficiency can result in reduced appetite, retarded growth, dry thickened skin and hair loss in severe deficiencies.
Copper is required for the development of bone, joint cartilage and connective tissues but also plays a role with metabolic and tissue anti-inflammatory enzymes. Deficiency can result in lameness in growing horses as well as anaemia.