The apparatus for determining the yield of milk by a milking machine, comprises a discrete sensor including a reception chamber and a measurement chamber. The reception chamber receives a float element mounted on a hollow rod (11) carrying a permanent magnet and a valve member received in the measurement chamber a vacuum gauge includes an array of reed relays electrically connected to a computing unit, including a similar array of pulse counters, and being connected to a pickup arranged in the area occupied by the permanent
magnet (13) as the level of milk in the discrete sensor rises to a predetermined level. A method for measuring the milk yield by a milk yield measuring device provides for the following operation: dividing a standard dose of milk into separate optimal milk doses by mean of a discrete pick-up (1) comprising a receiving chamber (5) and a measuring chamber (8) provided with a floating element (10) secured on a hollow rod (11) carrying a magnet (l3) and a valve (15) located in the measuring chamber (8) connected to the milk receiver (16); preliminary correction of said separate milk doses (2) by means a calculating unit (31) connected to a pick-up (35) located in the vicinity of the magnet (I5) at the moment when the desired level of milk
(2) is reached in the discrete pick-up (1) and effecting of the final correction of the preliminarily corrected separate dose of milk (2) to take account of the existence of a non- controlled portion of milk (2) in the measuring chamber (8) in the event of a change in the vacuum gauge pressure in the milk receiver (16), by means of a vacuum gauge (37) connected to the milk receiver (16), and of the calculating unit (31).