To formulate suitable diets for horses, nutritionists need to know both the horses` requirements for energy, protein and other nutrients, and the composition of the individual feedstuffs. Tables that list the average compostion of feedstuffs are available - such as the DLG-Futterwerttabelle fur Pferde in Germany or that produced by the National Research Council in the USA.
However, the danger of relying on standard values was highlighted at the Equine Nutrition Conference in Hannover, October 2005.
Professor Frieder Schwartz and colleagues at the Technical University of Munich and the Bavarian State research Center for Agriculture looked at rations fed under practical farm conditions. Their study involved 40 farms throughout Bavaria. Each farm housed an average of 50 horses. They collected samples of all main feedstuffs three times at 4 week intervals - a total of 159 feedstuffs.
They found that all forages, and oats, showed a great variation in content of calcium, crude protein and crude fibre and especially in mineral content.
First cut meadow hay - showed a wide range of digestible crude protein (DP) ( 31 - 76 g/kg DM) and digestible energy (DE) ( 7.6 -10.1 MJ/kg DM) . There was a very wide range of mineral content. The concentrations of both the major minerals, such as calcium and potassium, and the trace elements such as zinc and selenium, varied widely.
Ensiled grass is becoming popular feed for horses. It tends to be produced either as silage (containing 45-55% dry matter ) or as haylage which is drier (>65%DM) . The investigators looked at 36 samples. They found a wide variation in composition. The dry matter content varied from less than 30% to more than 70% DM. demonstrates. The differences are a consequence of the different procedures used for producing silage for horses.
All of the cereals sampled had low levels of major minerals and trace elements when compared to the requirements for horses.
For more details see: Variation in the nutrient composition of different feedstuffs for horses. Frieder J Schwarz, Heike Sliwinski, Manfred Schuster, Ewald Rosenberger. Proceedings Equine Nutrition Conference. Pferdeheilkunde (2005) 21, 9 -10.