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How to use the ratio between protein and energy

How to use the ratio between protein and energy

In Sweden the horse’s energy requirement is given in metabolizable energy (ME), and the unit is mega joule (MJ). In other countries the horse’s energy requirement can be given in digestible energy (DE) or net energy (NE). Roughly DE × 0.86 = ME and ME × 0.74 = NE.

The horse’s protein requirement can be given in relation to the energy requirement. In Sweden the ratio of gram digestible crude protein per MJ ME (g dCP/MJ ME) is used. Adult horses need at least 6 g dCP/MJ ME to fulfil the maintenance requirement of protein. If we for example buy forage with lower ratio than 6 g dCP/MJ ME we might have to add a protein supplement to our feed ration.

Growing horses’ protein requirements are higher; 13 g dCP/MJ ME from 3-4 month of age and then the ratio gradually decreases down to 6.5 g dCP/MJ ME from 19-36 month of age. The additional protein requirement for pregnancy and lactation is 12 g dCP/MJ ME.

Studies have shown that trotters in training fed forage with a ratio of up to 12 g dCP/MJ ME did not indicate any changes in heart rate, breathing frequency, plasma lactate and blood pH but performed equally well. The high protein intake from forage increased the muscle concentration of glycogen and the amino acid leucine in trotters in training which is positive for muscle recovery after exercise. Another study have also shown that forage with high CP content gives higher insulin release after feeding which is interesting for the high performing horse since insulin stimulates muscle glycogen storage and therefore benefits muscle recovery after exercise. Hence it can be interesting to aim for a higher ratio for forage to high performing horses.

Excess feeding of protein (and energy) should be avoided to obese and insulin resistant horses. When forage with high CP content can imply an increased insulin release a high ratio can instead be a problem for insulin resistant horses. It is still important to not fall below the horse’s calculated protein requirement. But for horses diagnosed with EMS or that has been found insulin resistant it is recommended to aim for forage with a ratio of 5-6 g dCP/MJ ME.

Sara Muhonen, AgrD

References:
Connysson M, Muhonen S, Lindberg JE, Essén-Gustavsson B, Nyman G, Nostell K & Jansson A. 2006. Effects on exercise response, fluid and acid-base balance of protein intake from forage-only diets in Standardbred horses. Equine Veterinary Journal (Suppl. 36), 648-653.

Essén-Gustavsson B, Connysson M & Jansson A. 2010. Effects of crude protein intake from forage-only diets on muscle amino acids and glycogen levels in horses in training. Equine Veterinary Journal 42 (Suppl. 38), 341-346.

Jansson A, Lindberg JE, Rundgren M, Müller C, Connysson M, Kjellberg L & Lundberg M. 2011. Utfodringsrekommendationer för häst. Inst. för Husdjurens Utfodring och Vård, SLU. (In Swedish)

Ringmark S & Jansson A. 2013. Insulin response to feeding forage with varying crude protein and amino acid content in horses at rest and after exercise. Comparative Exercise Physiology 9, 209-217.

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