Conductivity Measurement - Microcontroller

We are looking for design of a circuit which will return a value between 0 and 5v DC which corresponds to the resistance of liquid(milk). The circuit has source voltage of 5vDC and can be designed to output a PWM signal if needed. The probes are stainless steel spaced 1cm apart and will be used in apparatus to measure the milk flow coming from cows on dairy facilities. For this reason several electrical characteristics must be taken into account. Cows are very sensitive to stray current so research will need to be conducted to ensure that the circuit measuring the flow of milk will not produce voltage or current that could harm the cow. We would like the components to be simple and affordable as it will effect the base cost of the unit we are developing. Schematics will need to be provided as well as a description of how the circuit will work. In summary: a. Measure conductivity(resistance) of milk b. Do so without harm to the animal c. Circuit will return a value between 0-5vDC - This range will correspond to a resistance reading between 0 and 5k ohms d. Source voltage on circuit cannot exceed 5vDC - We can provide a PWM signal if needed e. Design needs to be simple and affordable f. Probes on metering device is 1cm apart and stainless steel g. Voltage used to measure cannot be DC as this will corrode the probes in liquid e. Schematics and description of operation must be submitted f. We are already using a microcontroller which will read the input of the circuit provided.