In a few published papers the utilised mstabolisable energy system for recording grassland productivity has been extended to calculated herbage intakes by grazing animals from records of their performance. First the energy needed to sustain the measured level of performance by the animals is calculated using published energy allowances for maintenance, lactation, growth etc. Then the amount of herbage that will provide the calculated energy requirement is estimated. Although there are considerable variations in the factors used to calculated energy allowances in the systems used in different countries, papers published in Britain recently have used the MAFF (1975) allowances to make these calculations.