Everything Explained Protein

Katie Williams M.Sc. (Dist) R Nutr

When I was a member of the Pony Club excessive protein was considered to be the cause of all evil! Although 20 years later considerable research has identified starch as the real culprit, many myths still exist about protein.

Protein is vital for good health as it can be found in all tissues in the body and enzymes, hormones and antibodies are also made of protein. The building blocks of protein are amino acids, some of which have to be supplied in the diet because the body cannot make sufficient quantities to meet requirements. Those that have to be supplied in the diet are termed essential amino acids and the ‘quality’ of a protein is often measured by the levels of essential amino acids it contains.

Lysine is the only amino acid, essential or otherwise, for which the horse’s requirement has been established. It is particularly important for youngstock, as a deficiency will limit growth and development.

Alfalfa as a Source of Protein

Alfalfa is a member of the legume family and so possesses the ability to ‘fix’ nitrogen from the atmosphere and incorporate it into the plant. Along with soya, which is also a legume, alfalfa is one of the most commonly used sources of protein in horse feeds.

The key features of alfalfa are:

  • Most of the protein in alfalfa is found in the leaf; in fact the leaf contains two to three times more protein than the stem.
  • The level of quality protein in alfalfa is very good, with lysine at 0.83% compared to wheat at 0.4% on a dry matter basis.
  • 3kgs of Alfa-A Original provides a 500kg horse in light work with 65% of their Crude Protein and 62% of their lysine requirement. NB: Grass and hay/haylage will supply the rest so a broad spectrum supplement is all that is needed to provide a balanced diet for most horses and ponies.

Dispelling Myths About Protein

It has taken some time but there is now fairly extensive research vindicating protein, which makes one question why protein was ever thought to be the cause of so many problems. The explanation may well lie with the laws governing the nutritional information that has to be listed on every bag of feed.

As the level of protein has to be declared on a bag of feed and the starch level doesn’t, protein has often been used as the measure of the ‘richness’ of a feed. With traditional cereal based compound feeds such as mixes and cubes, it usually follows that the higher the protein level, the higher the starch level as the feed provides more energy for a harder level of work. If high protein (and starch) feeds are being fed and a problem such as laminitis or colic ensues, it is fairly understandable that protein is believed to be the cause as this is the nutrient that the horse owner knows has increased when they look at the back of the bag. Until changes to legislation are made, it is likely that some horse owners will continue to blame protein for a number of problems.

Some of the diseases and problems that protein is wrongly blamed for include:

  • Protein causes laminitis – current thinking is that excessive starch from cereals or fructan (sugar) from grass is broken down rapidly, creating a very acidic hind gut. This results in the death of bacteria, which release toxins into the bloodstream that trigger a series of events that eventually result in the disruption of blood flow to the feet.
  • Protein causes azoturia – research has shown that high starch diets and not excessive protein intake are a contributing factor to muscle related problems now referred to as ERS. It is usually a number of factors such as reduced exercise, genetic predisposition and possibly even viral infections alongside high starch diets that combine to cause a problem.
  • Protein causes over-excitable behaviour – protein is rarely used as an energy source by the horse and over-exuberant behaviour is more likely to be due to an increase in energy intake, of which the horse owner may or may not be aware. The levels of energy in grass and hay/haylage vary throughout the year and even if the horse consumes the same amount of forage the energy intake may still increase through ‘hidden’ energy.

Where do I get more information on protein levels in my horse’s diet?

As feed manufacturers only have to declare the level of crude or ‘total’ protein on a bag, this doesn’t tell you much about the levels of essential amino acids in the feed. Most manufacturers will be able to tell you this information if you request it directly. If you would like a personalized feeding plan for your horse, including more information on key essential amino acid levels, then please contact the Dengie Feedline on 0845 3455115 or email feeds@dengie.com quoting Dengie Quarterly Newsletter Feeding Plan.