Protein is often the most underestimated and misunderstood element in a horse's diet.

The horse continually uses protein either to build new tissues, as in growth, or to repair worn out tissues. Protein is the main constituent of the organs (such as liver, heart, kidneys, etc) and tissues (such as muscle, tendons, ligaments, cartilage) and most of the bone matrix which comprises 20% of bone is composed of protein. Protein is required to develop muscling, and most body functions require protein in many different forms.

Therefore, a continuous and sufficient supply of protein is needed. The importance of an adequate quantity of protein in horse nutrition is easily demonstrated. Diets deficient in protein result in failure to grow normally and may even result in death. It is important to note that animals engaged in heavy production have much higher protein needs than animals not in full work i.e. in the paddock, etc.

The dietary requirements of animals are not only a matter of providing a sufficient quantity of protein, the quality of protein is very important. Proteins are made of approximately 20 amino acids in varying combinations. Amino acids are often described as the building blocks of proteins. Animals can only make about half of these amino acids and must therefore be supplied with the ones they cannot make. These are called "essential" amino acids. Protein quality is determined by the proportions of essential amino acids making up the protein.

Just as a pattern in a brick wall can only be built if there are sufficient of the different colours to make the pattern, so too does protein building rely on the amino acids all being present in the correct proportions. The most limiting amino acid in feeds commonly fed to horses is lysine, with methionine and other essential amino acids also being deficient. A horse will only utilise its dietary protein up to the lowest level of the limiting amino acid. A shortage of any one essential amino acid (E.G. Lysine or methionine or both) makes overall protein utilisation by the horse less efficient.

To minimise protein wastage and to maximise protein utilisation, a horse needs a scientific combination of essential amino acids designed to make as much of the protein present in its ration into utilisable protein as possible. As grains contain lower amounts of lysine and methionine and other essential amino acids than is required by the horse, and as the protein content of grains is quite variable, Ranvet has formulated a scientific combination of essential amino acids in a Palatable protein and grain concentrate supplement. The end result is a product called Promix.

The inclusion of a small amount of a protein concentrate, such as soyabean meal, cottonseed meal, tickbeans, lupins (500g - mature horse; 750g up to 3 years old) in the ration, plus the addition of 250g Promix will ensure that the horse does receive sufficient protein and that it will utilise the protein in the diet as efficiently as possible.

It is often said that high protein diets are detrimental to the horse in work, because the horse must use energy to break down the protein and excrete the excess nitrogen. However, poor quality protein in the diet is just as expensive for the horse to use as in an excessively high protein diet. Remember, a horse can only utilise the protein in its diet up to the level of the amino acid in shortest supply, therefore other amino acids present in excess of the requirement must be broken down and excreted. Addition of Promix to the diet will ensure that the amino acids already present in the ration can be utilised more efficiently.

Why add Promix to the diet?

It is not just important to supply the horse with a certain quantity of protein, it is the quality of protein that is the critical factor. Quality referring to the amounts and proportions of amino acids making up that protein.

Therefore, a diet may supply sufficient quantity of protein but the quality of protein is lacking, such that the horse can only utilise a portion of that protein. An example of this is the quantity of protein supplied by a typical grain/chaff/hay diet. Grains and many of the chaffs and hays contain less amounts of lysine and methionine (and other amino acids) than are required by the horse.

There are a number of ways to increase the level of lysine and methionine in the diet. One of these is to increase the percentage of protein meal in the diet. If this is increased to 1.0-1.2 kg protein meal per day, the required levels of lysine and methionine may be achieved, however the levels of all other amino acids are then present in far greater amounts than the horse requires. This excess proportion then becomes waste and must be broken down and excreted. The breakdown (or deamination) process requires energy which the horse can ill afford to use.

A more efficient way to overcome the shortage of lysine and methionine is to provide the horse with 500g of a protein meal and 250g Promix. By supplying the specific amino acids that are deficient saves the expense of increasing levels of all the amino acids. By feeding Promix, the horse will not be required to expend energy in the breakdown (deamination) of high levels of other non-essential and essential amino acids.

Put simply, the addition of Promix and a low level of protein meal to the ration, ensures that there is no deficiency of lysine and methionine (and other essential amino acids), all protein is utilised and there is no excess level of waste protein that requires energy to breakdown. The horse will put on condition and not expend energy otherwise useful for performance.

Stress and the horse in work - its effect on protein metabolism

All horses in work are under some degree of stress, whether it be physical or mental or both. Stress has been shown to significantly increase the breakdown of protein in the body, which leads to an increase in the requirement for protein. Therefore, provision of adequate good quality protein in the diet (i.e. addition of 500g of protein concentrate plus 250g of Promix) is extremely important if the horse is to maintain condition while in work and perform at its best.

Protein as a muscle building agent

Protein rich feeds and exercise are known to have a muscle building effect by stimulating the release of hormones concerned with the uptake by the cell of amino acids. The more amino acids taken up, the more protein produced. The more protein produced, the more muscle is laid down. However, if the amino acids in the diet are inadequate for protein building to occur, then maximum muscle building cannot take place. Addition of 500g of a protein concentrate plus 250g of Promix will ensure that the horse can get the maximum effect from the process occurring in its body.

What type of horses need PROMIX?

1. Horses in work

The protein requirements of the horse in work are in the order of 10-12% crude protein (i.e. 10-12% crude protein in the whole diet). This portion may be made up by protein from a number of sources. Most feeds used for horses contain some protein, however, as the quantity varies, so too does the quality. To ensure the horse in work gets sufficient quantity and quality of protein Promix should be fed on a daily basis with each feed (as amino acids cannot be stored) in addition to a protein concentrate.

Horses in work include racehorses, pacers and trotters, endurance horses, polo ponies, showjumpers and eventers.

2. Spelling Horses

Spelling horses are often overlooked when it comes to feeding. Many are put out in the paddock straight off a high energy, high protein diet for rest and recuperation. When horses are put out to spell at the end of a preparation, it is generally because they can no longer cope with the level of work that is being asked of them. The reasons for this are either loss of condition and inability to stand up to work, or lameness and other breakdowns. To enable the spelling horse to 'recuperate', he/she must be fed a well balanced diet and his/her requirement for protein is initially no lower than the horse in work. Protein will aid in the growth and repair of tissue which is used and abused during racing.

The spelling horse requires 9-11% Crude Protein in the diet (12% for the young, growing horse). Promix at a rate of 250g/day as well as a protein concentrate (500g/day) will provide this required level of good quality protein.

3. Dry mares (empty or during the first 8 months of pregnancy).

Dry mares (empty or during the first stages of pregnancy) require 9-11% Crude Protein in the diet. (These requirements increase towards the latter stages of pregnancy). Empty mares require protein for maintaining their body condition which is critical for normal cycling. The mare that is cycling normally will have a good chance of becoming pregnant (unless other detrimental health factors intervene). Pregnant mares should be fed a diet sufficient to maintain their condition at all times. A protein concentrate and the addition of Promix to a well balanced diet will provide the necessary quantity and quality of protein to these mares to maintain them in good condition.

PROTEIN DEFICIENCY

A deficiency of protein in the ration of the horse may result in the following deficiency symptoms.

- Depressed appetite

- Poor growth

- Loss of weight

- Loss of condition

- Loss of stamina

A deficiency of protein in the horse's diet occurs due to the variability of the protein content in hay, grains, chaffs, etc., that comprise the daily diet of a horse. If these components are of inferior quality or if fed in sufficient quantity, a deficiency will arise.

To guard against this deficiency, maximise protein utilisation and minimise protein waste, a horse requires a scientific combination of essential amino acids. This is designed to make as much of the protein present in its ration into utilisable protein as possible. (Utilisable protein describes that part of the dietary protein (or crude protein) which can be absorbed and utilised by the horse for synthesis of body proteins (such as muscle). The nearer the dietary protein approaches the body proteins in amino acid composition, the higher will be the proportion of utilisable protein).

PROMIX is such a scientific combination. It is not primarily a source of additional protein, but a formula to make low quality protein complete HIGH QUALITY PROTEIN.

The difference between utilisable protein and crude protein, is largely waste. This waste cannot be used as protein due to its poor amino acid balance. It can be partly used as an expensive source of energy and the excess nitrogen excreted as urea through the kidney.

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