Feeding alfalfa to breeding & youngstock

Why is Alfalfa so good for Breeding & Youngstock?

Breeders have heard that alfalfa is particularly beneficial for breeding and youngstock, but why does alfalfa deserve this reputation? Below our nutrition team explain in more detail the beneficial nutrients supplied by alfalfa.


Alfalfa is well known for supplying abundant amounts of protein. Along with energy, the overall amount of protein needs to be adequate in the diet to support optimal growth. Whilst the amount of protein in the horse’s diet is important, so is the quality of the 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.

Alfalfa Fact – how much protein and lysine does Dengie alfalfa supply?

Dengie’s Alfa-A range typically supply 12-14% crude protein and 0.7% lysine. For comparison the NRC Nutrient Requirements of Horses gives a reference value for mature cool season grass hay at 10.8% protein and 0.38% lysine. Alfalfa therefore supplies 1.8x as much lysine as average hay.

Whilst alfalfa is a very useful way of improving the nutritional quality of the forage ration, adding a pure alfalfa feed, such as Alfa-A Original to a hay only diet alone will not meet requirements in all circumstances. This is why grass is such an important part of the lactating mare’s diet.

A 500kg mare at 1 month lactation requires a staggering 84.8g of lysine compared to 30.1g for the horse in light exercise. A diet of 10kg of average hay and 2.5kg of a pure alfalfa product will supply 55.5g of lysine and so there’s still a shortage. The other factor to consider is that not all hay is average and there will be large variations between years and batches. A forage and alfalfa only diet for breeding and youngstock should therefore be topped up with quality protein and other nutrients by using the advised amounts of a stud specific feed balancer, such as Performance+ Balancer or if required mix/cube; especially if the mare isn’t at grass.

Dispelling a myth- excess protein causes Developmental Orthopaedic Disease (DOD)

A myth that has been around for years is that excess protein results in an increased risk of Developmental Orthopaedic Disease (DOD). This myth has been dispelled and it is known that rapid growth encouraged by high energy supply, combined with a trace mineral deficiency are the key things to watch out for.

The importance of calcium

Alfalfa is also well known for its abundant calcium levels. Calcium is found predominantly in bones and also plays a role in muscle contraction, cell membrane function, enzyme regulation and blood coagulation. Any deficiency of calcium will mean that stores in bone are drawn upon to meet demand and therefore a deficiency in calcium in young horses can result in skeletal deformity. It is not only the intake of calcium in the youngster that is important, but in the mare as well, as the majority of calcium present at birth is deposited in the 8th to the 11th month of gestation.

It is not only the amount of calcium in the diet that’s important, but its ratio to other minerals particularly phosphorus. An excessive intake of phosphorus even with an adequate intake of calcium can result in calcium deficiency as they compete for the same site of absorption. Ideally the total diet should provide a ratio of in the region of 1.5-2:1 calcium (Ca) to phosphorus (P).

Alfalfa Fact – how much calcium does Dengie alfalfa supply?

Dengie’s Alfa-A range of feeds supply 1.5% calcium. For comparison the NRC Nutrient Requirements of Horses gives a reference value for mature cool season grass hay at 0.47% calcium. Alfalfa therefore supplies 3x as much calcium as average hay.

Dispelling a myth – alfalfa supplies excess calcium

Well actually this one could be true if alfalfa was fed as the sole diet. Whilst alfalfa hay is commonly fed in other countries, here at Dengie we put an upper feeding rate on the pure alfalfa products of 500g per 100kg of bodyweight daily to avoid excessive nutrient supply.

Going back to the calcium to phosphorus ratio, alfalfa has a ratio of 6:1 Ca:P which is higher than the 2:1 we try to achieve in the total diet. However when we talk about Ca:P it is important to remember we are talking about the total diet and not just 1 element. A 500kg horse having 10kg of hay with the addition of 2.5kg of alfalfa will result in a Ca:P ratio of 2.6:1 and also supply sufficient calcium and phosphorus throughout gestation for example. Ratios as high as 6:1 Ca:P haven’t been found to cause any issues as long as phosphorus requirements are met. Whilst there is unlikely to be any advantage to feeding calcium in such excessive levels it isn’t going to cause harm.
Again it is important to remember that average figures are just that and not all pastures or forages supply this amount of calcium and some can be much lower. For breeding stock particularly it highlights the value of getting forage analysed as low calcium forages can easily be supplemented with alfalfa to improve nutrient supply where required.

Energy from Fibre

Along with protein, having adequate energy in the diet is vital for optimal growth. How useful a fibre source is to a horse in providing energy is dependent on its digestibility. This is determined by many factors including environmental conditions, but particularly by the age of the plant at the time of harvest. The more mature the plant the less digestible it is. Dengie alfalfa is cut when the plant is not fully mature and this combined with high temperature drying results in a more digestible, highly nutritious fibre source.

In recent years there has been increased interest in looking at the effect of energy source on growth and long term health. Focus in particular has been on lower sugar and starch rations and the benefits to long term insulin sensitivity, behaviour and stress at weaning and digestive health to name just a few. As with the adult horse, high starch rations at the expense of fibre has its consequences.

Alfalfa fact- how much energy does alfalfa provide?

Dengie alfalfa naturally supplies around 10MJ/kg of digestible energy. When oil is added to alfalfa as with Dengie Alfa-A Oil 12.5MJ/kg digestible energy can be achieved which is equivalent to a stud mix/cube but with only 2% starch.

Dispelling a myth- An alfalfa based ration can’t supply breeding stock with sufficient energy

As we have seen above, when combined with oil, alfalfa can supply as much energy as a traditional stud feed and as long as it is combined with a stud specific balancer, such as Dengie Performance+ Balancer, can provide a good all round balanced ration.

In practice whether it can meet the energy demands of breeding stock depends on what type of horse is being fed. A Jan/Feb foaling mare has her highest energy demands when grazing quality is poorest and reliance on conserved forage is high. Alfalfa can make a great addition to the ration here, but extra energy may be required. Conversely a mare foaling in May/June has her greatest energy demands through a period of time when grass is typically abundant and is likely to thrive on a fibre only ration with the addition of a stud specific balancer.