Calculate from kg DM to kg feed

The dry matter (DM) content of forage is the dry material that is left when the water content of the forage has been deducted (Figure 1). Since water does not contain any nutrients it is very important to know the forage’s DM concentration to be able to value the forage and to be able to calculate feed rations. How much water forage contains varies greatly between pasture, silage, haylage and hay which clearly show in Figure 1. When sending a feed sample for analysis the DM concentration is included in the analysis response. Sometimes it is necessary to calculate the forage’s nutritional content from kg DM to kg feed and vice versa. For example if you have calculated the horse’s requirements in kg DM you have to recalculate them into kg feed to know how much feed to weigh up when it is time to feed the horse. Below two examples for calculations are shown, how to calculate energy and protein values from kg DM to kg feed and from kg feed to kg DM for the hay and silage from Table 1.

 

 
Arithmetic examples

From kg DM to kg feed:
 
Hay 82% DM (82/100 = 0.82)

11.6 MJ/kg DM                      →           11.6 × 0.82 = 9.5 MJ/kg feed

113 g dCP/kg DM                  →           113 × 0.82 = 93 g dCP/kg feed
 
Silage 45% DM (45/100 = 0.45)

11.6 MJ/kg DM                     →            11.6 × 0.45 = 5.2 MJ/kg feed

127 g dCP/kg DM                 →            127 × 0.45 = 57 g dCP/kg feed
 
From kg feed to kg DM:
 
Hay 82% DM (82/100 = 0.82)

9.5 MJ/kg feed                    →              9.5 / 0.82 = 11.6 MJ/kg DM

93 g dCP/kg feed                →              93 / 0.82 = 113 g dCP/kg DM
 
Silage 45% DM (45/100 = 0.45)

5.2 MJ/kg feed                   →              5.2 / 0.45 = 11.6 MJ/kg DM

57 g dCP/kg feed               →              57 / 0.45 = 127 g dCP/kg DM
 
Sara Muhonen, AgrD