Supporters of the organisation Farmers for Action used tractors to block a Robert Wiseman Dairy processing plant near Bridgwater, Somerset, last night.
They are protesting at the price they are paid for a litre of milk. In the last three months the price paid per litre has dropped by 2 pence and will drop by another 2 pence by 1 August.
Farmers are hoping the dairy will reverse its decision and pay them the money they have lost but many fear the shortfall will force them out of business. Some farmers are being paid less for their milk than the cost to produce it.
Robert Wiseman Daries have released a statement saying they understand the farmers' position but that they cannot fund the milk price at the previous level.
James Small, 36, a livestock farmer on the Mendip Hills in Somerset said he supported his dairy colleagues at the protest near Bridgwater.
Mansel Raymond the National Farmers Union dairy board chairman told MPs this week that farmers "will not have the heart to go into the winter" if milk prices stay where they are.
The latest cuts will see farmers paid around 25p a litre for milk, but Mr Raymond said the cost of production was 29p a litre, meaning a sale price of 29.5p was the minimum they needed to remain viable.