Hundreds of farmers blockaded processing plants into the early hours of the morning in a protest against the price they are paid for milk.
Supporters of the organisation Farmers for Action (FFA) used tractors to block a Robert Wiseman Dairy processing plant near Bridgwater, Somerset, on Thursday night, while other farmers gathered outside an Arla plant in Ashby-de-la-Zouch, Leicestershire, and another plant in Leeds.
Dairy farmers are furious about cuts of up to 2p a litre in the amount they receive from major milk processors.
Many fear the shortfall will force them out of business.
The action is the latest in a series of protests by farmers who are angry that they are to be paid less for their milk than the cost to produce it.
David Handley, chairman of FFA, warned blockades could form again on Friday.
Speaking from the blockade near Bridgwater, Mr Handley told the BBC that if the financial situation for farmers continues then they could be forced to make the "ultimate sacrifice" and cut off the milk supply at source, keeping it on the farms.
Mr Handley said: "These people have got greedy, and they have squeezed us and squeezed us to the point we have got to.
"We have got to fight for the industry because if we don't the industry is going to go."
Mr Handley said there were around 550 farmers and 120 tractors between the Bridgwater plant and a nearby Morrisons supermarket distribution centre.
Andrew Hemming, vice-chairman of FFA, said he and about 400 farmers gathered outside the Arla plant in Ashby.
He said: "We've had a lot of support, not just from FFA members but a lot of other farmers too. It just shows the strength of feeling there is."
Mr Hemming said FFA was specifically targeting Arla, saying: "They are one of the big three who are trying to kill the dairy industry altogether."
James Small, 36, a livestock farmer on the Mendip Hills in Somerset, supported his dairy colleagues at the protest near Bridgwater.
He said: "There are an awful lot of young people, who obviously want to have a future in dairy, and farming in general, and they're voicing their concerns about whether there will be a future given the current crisis.
"The sense of frustration and anger is palpable amongst the people here, they all feel a huge injustice about it all.
"Processors like Wiseman or Arla or those types of companies are being dictated to by the major retailers - they are the ones who are really forcing the price down."
Milk farmer Anthony Rew, from Newton Abbot, Devon, said: "There was a price cut about a month or so ago of about a penny and a half on our milk and now three of the large buyers have announced a price cut starting from 1 August and that's really stimulated the dairy industry into action.
"This summer has been terrible, farmers have been producing below the cost of production, they've been paid below the cost of production for a while and now this will be three and a half pence to four pence below the cost of production that they are getting paid.
"It's really put the industry in an unsustainable place."
Dairy farmers fear the cuts to payments will force them out of business, pushing up the price of milk to consumers in the long-term.
National Farmers Union dairy board chairman Mansel Raymond 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.
Dairy Crest is one of a number of milk producers that have slashed the price they pay farmers for milk after seeing the value of cream plummet this year.
It has admitted its milk price cuts "put pressure on our supplying farmers".
Farming Minister Jim Paice said: "These price cuts are a severe blow for dairy farmers.
"Government cannot and should not set prices but I will do everything in my power to get all levels of the supply chain to make the real changes needed to guarantee the industry's long-term future."
A spokesman for Robert Wiseman Dairies said: "We fully understand the strength of feeling amongst dairy producers and continue to engage with those with an interest in the dairy supply chain.
"It is important to stress we are not in a position to fund a milk price at the level it was prior to the global collapse in the value of cream.
"It is our hope that the market for liquid milk and bulk cream which is at the core of this issue will quickly find a balance which will allow us to return improved prices to farmers."
Celebrity chefs Jamie Oliver and Hugh Fearnley-Whittingstall have stepped into the debate and urged the public to boycott some supermarkets over cuts to the price of milk.
In a letter to The Times, Oliver and Fearnley-Whittingstall said it was "shocking" that many dairy farmers were to be paid less for their milk than it costs them to produce it, adding that the industry was becoming "unviable".
Calling on consumers to boycott supermarkets that continued to use milk as a loss leader, they warned that thousands of family businesses would fail and the landscape would be threatened if the industry breaks down or becomes "super-industrialised".
But the British Retail Consortium said supermarkets were the "wrong target".
Spokesman Richard Dodd said: "They're actually the best payers for milk. Currently, 11 of the top 12 best-paying milk contracts are contracts paid by supermarkets."
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