They also held marches to campaign against processors cutting up to £2 a litre off prices.
Their cause has been backed by celebrity chefs Jamie Oliver and Hugh Fearnley-Whittingstall who urged the public to boycott some supermarkets.
But the British Retail Consortium said supermarkets paid well and it was other purchasers who should be scrutinised.
The Robert Wiseman Dairy processing plant off junction 24 of the M5 near Bridgwater in Somerset was blockaded by between 600 and 700 farmers with their tractors on Thursday night.
Stephen Britten from Farmers for Action at the Arla plant in Leeds
Organisers there delivered a letter to the site manager asking for the reinstatement of previous prices and said they would not move until they got a response.
Farmer James Small, from Somerset, said at the Bridgwater protest: "I think it's a fantastic showing of unity here.
"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.
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