DairyNZ set up its Greenfield Project to investigate whether a fully automated milking system can be used on New Zealand’s dairy farms. So how do they get the cows to milk themselves?

The aim of the automatic milking system (AMS) is to reduce the amount of labour needed to run a farm. This involves getting the cows to move themselves around the farm and by using a robot to milk the cows.

The cows on the Greenfield farm have to be taught how to use the milking robot (called Merlin) and how to take themselves to be milked. This is done by offering rewards (called ‘operant conditioning’) and getting them used to it slowly (called ‘habituation’).

Teaching the cows to use Merlin

The robotic milking relies on cows learning how to use the robot (Merlin) to get themselves milked.

First, a cow is walked through the machine with both of the gates open. Then she is held in the machine for 4–5 minutes without being milked. After doing this 2–3 times, the farmer helps the cow to be milked by Merlin by pushing her gently into place for the robot to attach the milking cups. Crushed barley is given to the cows as a reward each time they are in the machine. (This is like giving them lollies for being good.)

Teaching the cows to take themselves to be milked

A milking system that is fully automated requires the cows to get themselves to the dairy for milking (the farmer does not need to go out and fetch them). Once the cows can do this, they can go and get milked at any time, day or night. The aim is to get a steady stream of cows through the dairy so that the milking robot (Merlin) is always in use.

Training cows to use the gates

On their first day on the farm, the cows are walked around the property. They do a loop from the paddock, through a slightly open gate to a water trough, along the race to Merlin and back to a new paddock. One-way gates stop the cows going backwards along this loop. The cows are taught to use the gates by leaving them ajar for a few days and giving them access to water, grass or barley once they go through.

When the Greenfield farm was first set up, the cows learned that they got rewards for going through the gates, and they ended up visiting the dairy shed too often. As a result, selection gates were installed. These control whether the cow is sent to the dairy or back to the paddock.

Determining when a cow is due for milking

Electronic information on each cow is stored in a computer and is used to determine whether a particular cow is due to be milked or not. When the cow enters a selection unit, a signal from the computer directs the gate to open, either letting the cow back into pasture or directing her up to the dairy for milking.

Cow behaviour leads to modifying gates


Another problem at the start of the project was that some of the cows learned to open the one-way gates in the wrong direction. This could have happened when a cow reached over the gate to get to some grass, accidentally pulling the gate open. The reward – perhaps access to fresh pasture – would have reinforced the behaviour. The next time she was in the selection unit, the cow would have nudged her head against the gate again and eventually caused the gate to open.

Again, access to fresh pasture on the other side would cause her to keep repeating this behaviour and improve her gate-opening technique. As a result, the gates were modified to stop this happening.

Investigating whether cows can learn from other cows

The scientists think that cows learn to walk through the selection units to the dairy much faster if there is an experienced cow for them to follow. The team at the Greenfield Project are investigating whether cows already on the farm can teach new cows to use the system without any help from the farm staff.

    Published 1 March 2006