Basis of feed value calculations - Horses

Agriculture

The feed energy value for horses is calculated similarly as for ruminants. The composition information needed for feed value calculations can be obtained from the feed analysis or from the Feed Tables, and the digestibility coefficients from the Feed Tables.

Energy value

The feed energy value for horses and ruminants and also feeding recommendations are based on metabolizable energy (ME), and they are given as megajoules (MJ) (Kaustell ym. 1997). 

The concentration of metabolizable energy is calculated according to a British method (MAFF 1975, 1981, 1984). For further information on comparison of energy evaluation systems, see: Kaustell, K., Tuori, M. & Huhtanen, P. 1997. Comparison of the energy evaluation systems of feeds for dairy cows. Livestock production science 51, 3: 255-266.

Concentrate feeds

The concentration of metabolizable energy in concentrates (feed classes 1-5 in Feed Tables) is calculated based on the amount of digestible nutrients in the feed using the following equation (Schiemann ym. 1972, MAFF 1975, 1984):

ME (MJ/kg DM) = (15.2 × dCP + 34.2 × dCFat + 12.8 × dCF + 15.9 × dNFE)/1000 

where:
dCP = digestible crude protein, g/kg DM
dCFat = digestible crude fat, g/kg DM
dCF = digestible crude fibre, g/kg DM
dNFE = digestible nitrogen free extract, g/kg DM.

The concentration of digestible nutrient (i.e. dCP) is calculated by multiplying the concentration of nutrient (i.e. CP) with its own digestibility coefficient (i.e. CPd). The digestibility coefficients for different nutrients are given in Feed Tables.  

 

Forages

The concentration of metabolizable energy in forages is calculated based on the digestible organic matter concentration in DM, i.e. D value. D-value is announced as grams in feed dry matter (g/kg DM).  

Silage, grass:ME, MJ/kg DM = 0.0160 MJ/g × D value (g/kg DM) 
Hay, haylage 1):  ME, MJ /kg DM = 0.0169 MJ/g × D value (g/kg DM) - 1.05 
Straw: ME, MJ /kg DM = 0.0140 MJ/g × D value (g/kg DM) 
Whole-crop cereal silage: ME, MJ /kg DM = 0.0155 MJ/g × D value (g/kg DM) 

1)Haylage’s dry matter over 500 g/kg 

Protein value

Feed protein value for horses is expressed as digestible crude protein (dCP).
dCP (g/kg DM) = Feed crude protein concentration (g/kg DM) × feed crude protein digestibility


Example:

  • Feed crude protein concentration is 150 g/kg DM
  • Feed crude protein digestibility is 0.74 (the digestibility coefficients are obtained from the common Feed Table for ruminants)
  • Digestible crude protein concentration = 150 × 0.74 = 111 g/kg DM