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NCR calculations

Minerals and vitamins

The requirements for vitamins and minerals are calculated from the NRC (2007) norm (recommended amounts). The NRC norm for minerals and vitamins is the accepted norm throughout the world today and is revised at irregular intervals. It represents the cumulated results and experience of equine nutritional research globally. Some changes to the NRC norm have been included in the program following recommendations from, among others, Professor H. Meyer in Germany and from further collaboration between Nordic horse nutritionists.

It is important to recognise that the NRC norm is a minimal norm. This means that it is advisable to increase requirements by approximately 25% to secure the provision of sufficient amounts of specific nutrients under practical feeding conditions. In the current versions of the computer program we have already created this transformation from minimal norms to what we have termed "optimum norms" for most nutrients. The requirements for nutrients as given in the program will therefore be the optimum norm. When the amounts of a particular nutrient provided by the diet are below a certain limit (this value is usually the NRC recommendation), the program issues a warning, and you are prompted to increase the amounts of the nutrient by changing the diet of the horse. The norms are generally provided as equations where you have to input relevant information about the particular horse you are formulating the diets for. Information usually required for this is:

  • Body weight
  • Age and growth rate of young growing horses
  • Stage of pregnancy or lactation of reproducing mares
  • Training intensity or level of exercise


It is common to subdivide the requirements into

Maintenance requirement: The amount of a nutrient which is required to maintain the body pool of that nutrient. The maintenance requirement for energy is the energy used to keep the cells, tissues and organs of the horse alive and running, to maintain body temperature and keep a constant body weight.

Production requirement:
The amount of a nutrient which is used by the horse for production of milk, a foetus, or for carrying out a certain amount of work.

The temperament of the horse will influence the requirement for energy and hence for other nutrients as well. Easily agitated and "excitable" horses have a somewhat higher energy requirement than more docile breeds. Excitable horses will also use more energy when undergoing the same work load or training intensity as more docile horses. Thus there is an important need for individualisation in the feeding requirements of horses, not only where the composition of the diet is concerned, but also when it comes to the calculation of requirements. A good computer program can provide for this level of customisation.