Recent German Developments in the Formulation of Energy and Nutrient Requirements in Horses and the Resulting Feeding Recommendations

The recent review of the German feeding standards for horses results in a change in recommendations for protein and energy. Part of the new approach was presented by Zeyner and Kienzle at a recent conference in the United Kingdom (Ellis et al. 2010, The impact of Nutrition on Health and performance of horses, European Association of Animal Production (EAPP) publication 128) and illustrated the proposed new system for feed evaluation with respect to prececally digested protein and metabolizable energy. This in turn is linked with an updated formulation of requirements. The major areas identified for change were the energy and nutrient requirements for mares as well as the energy requirements for exercise. A new growth curve for the fetus and the inclusion of fetal oxygen consumption form the basis of the new structure for the description of requirements during gestation. The allometric model for lactation is still unsatisfactory because of the wide variation in published data related to milk yield. Although the new recommended model is a compromise, it seems to be reasonably adjusted to the actual needs of the foal. The accurate determination of energy requirements for exercise is a problem in practice. Using the heart rate as a predictor of energy expenditure enables an estimate of the demand for energy to be made by means of a direct signal from an individually exercising live horse. However, the proposed method to allow for the integration of anaerobic energy metabolism still needs experimental confirmation. Finally, aspects of behavior are intensively discussed as a non-nutrient part of requirements. The recommendation to limit starch intake per meal and to have a minimum recommended intake of roughage should help support the health of the digestive system and reduce the risk of nutrition-associated behavioral problems.