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Grazing Requirements

Understanding Ranch Businesses

The National Research Council (NRC) has done extensive work to determine the caloric requirements of animals in different physiologic states (maintenance, pregnancy, lactation, growth, etc.) under different environmental conditions and various levels of weight gain, etc. Ranch Vision uses this information to calculate the amount of grass energy required to meet the nutritional needs of the animals on your ranch.


A Grazing Unit Month (GUM) is a unit of measure for grass energy. The GUM is the amount of forage required to provide 10 megacalories (Mcal) of net energy per day for one twelfth of the year. This is approximately equivalent to the energy requirements for one month of a 1000-lb (450 kg) dry cow in late pregnancy and is roughly equivalent to an Animal Unit Month (AUM).


Ranch Vision projects the grazing requirements of the various grazing livestock enterprises in terms of GUM.

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