Do Protein requirements vary

Do Protein requirements vary?

Whether your horse is growing, mature, in work (and the type of work), pregnant or has a foal at foot; each will determine the amount of protein that you have to give your horse.

The requirement for protein depends on the function of the horse and the work they are in and the requirement is dependant on not only the quantity but also the quality of the protein available in the diet. This can be determined by the amino acid composition and digestibility, and this will determine the amounts of protein that you have to give the horse.

Protein requirements for pregnancy and lactation:

Pregnant mares that are not lactating do not require protein in excess of their maintenance requirement until the last trimester of pregnancy. The quality of protein in the diet at this time should be given priority.

Since approximately 65% of foetal growth takes place in the last 3 months of gestation, protein requirement will increase during this period. It is estimated that foetal placenta retains 77g of protein per day.

The protein content of milk is highest in the early stages of lactation, and declines gradually as lactation proceeds. Milk production (kg/day) depends on both protein and energy intake. A mare’s milk contains on the average between 2.1% protein in early lactation, with a drop to 1.8% protein in late lactation.

Protein requirement for lactation is calculated as digestible crude protein per kg of milk produced. High quality stud feeds such as GAIN Stud Mix/GAIN Stud Cubes contain excellent sources of protein to ensure there is adequate quantity and quality of protein in the diet to optimise milk production.

Protein requirements for growing horses:

The quality is of particular importance for growing horses. Lysine is usually the first limiting amino acid (the first amino acid to come into short supply in the diet). High quality sources of protein in the diet include hi-pro and full fat soya, alfalfa (Lucerne), milk based proteins (particularly useful in diet of foals/weanlings, sunflower meal and peas.

The requirements for higher amounts of good quality proteins are greater for growing horses than for older horses. Young horses have a smaller digestive tract in comparison to a fully-grown horse and hence have a smaller feed intake than adult animals. Therefore, the concentration of digestible crude protein must be higher in the diets of young growing horses than of any other category.  GAIN Foal Pellets contain 20% protein and are produced to feed at a rate of 1-2kg/100kg bodyweight per day.

An optimal ratio between energy and protein is required for a balanced growth. The demands for protein per unit of energy decreases as the horse gets older. The requirement for the amino acid lysine also declines with age.

At ages of 3, 6,12 and 18 months, the requirement for lysine is 0.7, 0.5, 0.4 and 0.4 grams per MJ of digestible energy, respectively.

Protein requirements for horses in work:

Training or work requires the same energy-to-protein ratio as maintenance (i.e. 5.2 grams digestible protein per MJ energy). The increases in energy intake required during work therefore increases the protein requirement proportionately.

For heavily exercised horses, protein allowances are more likely to become too high rather than too low. Excess protein in the diet is not desirable from both a cost and horse health perspective. Excess protein has to be filtered through the kidneys and excreted, leading to increased water intake and increased urine production. 

Ammonia build up in stables is then a more likely occurrence. Choose an appropriate concentrate for horses in work that will meet both their energy and protein requirements when fed at the recommended rates. 

There are many suitable performance products in the GAIN Equine Nutrition range. If you are unsure which product best suits your horses requirements its best of speak to one of our team of technical advisors.

Joanne Hurley is a nutrition specialist with GAIN Equine Nutrition. She holds a Masters in Animal Nutrition and Production from UCD. Joanne can be contacted by email at

Mailing List

Keep up to date with the latest products, offers and news from GAIN Equine Nutrition

This field is for validation purposes and should be left unchanged.