Feed energy - Dutch system
Feed energy system
The Feed Unit Milk (VEM), the Dutch feed energy system, is an energy parameter for dairy farmers. It represents the net energy content of a product for lactating cows. For beef cattle the Feed Unit Beef Cattle Intensice (VEVI) is used.
The Feed Unit Milk is related to the energy content of 1 kg of standardized barley (barley with a specific hectoliter weight and starch content, etc.). By definition, the energy content of this kg of barley is set at 1,000 Feed Unit Milk. Because Feed Unit Milk is a relative value, it has no unit.
The choice to create a nutrient without a unit makes comparisons easy in practice. For example, if a product contains 1100 Feed Unit Milk, this means that a product contains 1.1 times the amount of energy in 1 kg of barley (or 10% more energy than barley). In ration calculations, it is also easy to work with Feed Unit Milk; for example, when the energy density should be 1,000 Feed Unit Milk /kg dry matter.
In other feed evaluation systems, energy may be expressed in mega joules per kg of product (MJ/kg). The Net Energy Lactation (NEL) of 1 kg of barley is 6.9 MJ NEL – in other words, 1,000 Feed Unit Milk = 6.9 MJ NEL.
The Feed Unit Milk is calculated based on the level of digestible crude protein, digestible organic matter, digestible crude fiber, digestible crude fat and digestible carbohydrates (sugar, starch, other carbohydrates). This shows that digestibility (measured as Digestibility Coefficient of Organic Matter) plays a major role.
It also means that the energy content in roughage like grass can be strongly influenced by the time of harvest. Older grass contains more lignin, has a lower digestibility, and thus a lower Feed Unit Milk content.
To produce 1 kg of FPCM (Fat-Protein Correct Milk), milk with 4% fat and 3.3% protein, a cow needs about 460 units of Feed Unit Milk.
A cow producing 30 kg of milk needs about 19,000 Feed Unit Milk. Of this, about 5,300 units are needed for maintenance, the remainder for milk production.
Feed Unit Milk is analyzed in the following analyses: