What’s so important about protein?

20 Jul 2021

By Dr Vicki Glasgow, Harbro Nutritionist

Recent events and myths surrounding the above topic have prompted me to revisit an old favourite of mine – protein. There seems to be a vast array of misinformation out there, which can always cause problems in the general horse population if allowed to spread unchallenged. 

Protein is one of six important nutrients that horses require to live, reproduce and work. Apart from water, no one nutrient is more important than another. Protein is not a magical ingredient but along with the other nutrients, it is a vital component of your horse’s feed. To clarify from the outset – higher protein levels will not send your horse loopy. Some high protein competition or conditioning type diets will also be higher in energy and sometimes starch and it is the effect of excess energy, not protein that you may be experiencing!

Proteins are made up of amino acids (protein’s building blocks) linked in chains. There are 22 amino acids, 10 of which are essential, meaning that they must be provided in the horse’s diet. The non-essential amino acids are manufactured by micro-organisms in the horse’s gut or are produced by processes in the body. Protein is required for body tissue growth and repair. All of the body tissues and organs in the body contain significant amount of protein. It is essentially a structural component of the body present in muscles, bone, skin, hair and hooves. It is also an important component of the enzymes and hormones in the body, important to metabolic processes and functions.  

Horses that do not have enough protein for their work level, cannot build muscle as they are using any protein provided to maintain the status quo within their body. Any leftover protein will be utilised for running repairs on muscle tissue, damaged by hard work.


Quality protein
When nutritionists refer to quality protein they are basically describing the makeup of that protein and how utilisable that protein is by the horse. Crude protein (as appears on your feed label) is as it sounds –crude! 
Horses have a requirement for specific, essential amino acids in a specific ratio (ideal protein) and the better quality a protein is, the more essential amino acids it contains. Nutritionists can utilise good quality protein sources along with some synthetic amino acids (lysine, methionine etc) to ensure that feeds are correctly balanced for the age and work level of the intended recipient. 
Quality protein, with the correct balance of essential amino acids, is very important for young growing horses. Working horses, especially those expected to perform at reasonable levels, also require good quality protein in their feed, to help repair muscle damage due to hard exercise or training sessions and to enable them to build new muscles. Elderly horses also have a higher requirement for quality protein as their digestion starts to become compromised.

Liebig’s barrel
Liebig was a German scientist who used the image of a barrel, with uneven staves, to explain how biological processes are limited by the nutrient in the shortest supply.
If we apply this concept to muscle growth and repair, so essentially that holy grail of a fabulous topline, then amino acids (proteins building blocks) become a key factor. The level of the water (in this case muscle/topline) can only rise as high as the nutrient in the shortest supply. This image helps to see that not only is protein required but that protein has to be of a good quality, so that it provides all the building blocks required to lay down muscle. 
If we stretch this image further, to then include other nutrients and environmental factors, then the whole puzzle can be completed. I have seen people throwing protein at their horse as somebody has told them that their horse needs amino acids or soya, to no avail. This is because yes, their horse probably does need more quality protein but it also needs the other nutrients to support this!  
Energy level of the diet is also key to enable the horse to lay down muscle. In most of these scenarios a readjustment of the diet, to include a good quality oil, results in the desired effect, without causing the horse to become fizzy. Ironically if the horse does not have enough energy supplied to utilise the protein, then the body has to go through processes to expel the protein. This process, called deamination, is energetically demanding and so energy is wasted, making matters worse.  
Then of course, one of the other staves in the barrel is that of correct work, which is a topic for a different expert. If it is missing then the liquid can only rise to a certain level!

Protein supply
Horses will get protein from everything they eat, but obviously some sources provide more than others. Some of the more common, high quality protein sources you would hope to see on a feed label for a growing horse or hard working horse diet would be soya bean meal (Hipro or full fat varieties), milk powders, synthetic amino acids (lysine, methionine, threonine).  
Forage (hay and haylage) can be very variable when it comes to protein levels and for stud farms, where there are lots of young, growing horses and heavily pregnant mares etc, then the quality of the forage is key to a successful feeding regime. Grass is a great source of protein during the grazing season. Unfortunately it can also be high in fructans which many horses cannot cope with and so for the majority of horses has to be restricted.

If you are feeding recommended levels of a good quality compound feed, selected for the correct level of work for your horse then you can be assured that your horse is receiving the correct quality and quantity of protein. 
If, however, you are unable to feed the recommended amount due to having a good doer or a horse which has a restricted appetite then a balancer pellet will fit the bill. Balancers are a great way of providing your horse with all the protein, vitamins and minerals they require in as small an amount of feed as possible. They are designed to be fed along with bagged forages primarily, with oil, sugar beet and cereals added in according to work level as your energy sources.  

Protein is one of the vital nutrients a horse requires, and it should be easy to spot if your horse is deficient in protein (poor topline, rough dull coat, poor hoof quality, not shedding in the spring as quickly as they should) or is receiving an excess (great coat and hoof quality but urinates a lot and has a very strong smell of ammonia in the stable, also produces a lathery sweat with very little exertion).  
If in doubt always select a good quality feed, selected for the level of work and age of your horse and feed at the recommended level. If you cannot do this then use a balancer pellet in the correct proportion to top up your feed or use it on its own with forage and straights as required. 

Contact your local Harbro Country Store for feeding advice www.harbro.co.uk/country-stores



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