Farming leaders are meeting for an emergency summit as falling milk prices push those in the industry to "sheer desperation".
Protesters have been taking part in the Milk Trolley Challenges, blockading distribution centres and even bringing cattle into supermarkets to raise awareness of their plight.
The challenge sees farmers removing all cartons of milk from shops including Asda, Morrisons and Lidl before paying for it and taking it away, or dumping it at the checkout.
Milk prices have been falling steadily - with Arla announcing a price cut of 0.8p per litre, taking the standard litre price to 23.01p for its UK members.
Farmers estimate that it costs between 30 and 32p to produce each litre of milk - meaning some are losing almost 10p per litre.
A survey of milk drinkers found they would be willing to pay £1.28 for four pints of milk. Supermarket prices currently range from 89p to £1.
The four main farming unions, the NFU Cymru, the NFU, NFU Scotland and the Ulster Farmers Union, will meet with farmers in London to discuss the issue.
David Handley, chairman of Farmers For Action (FFA), is attending the summit, which will also examine prices paid to arable and lamb farmers.
"This weekend has been very busy in terms of Milk Trolley Challenges and there was a major protest last night outside an Asda distribution centre in Wigan," Mr Handley said.
"It is, purely and simply, to keep piling the pressure on to the retailers and to the food service sector. This is all in their hands.
"They can do something about the current issues that face the industry.
"We are not asking them to put prices up to shoppers, we are saying there is such a margin between the farmgate price and the price the retailers are charging customers.
"Their response is there's too much milk, they give every excuse under the sun.
"We understand it is difficult for retailers at the moment but that is their problem, not ours and we don't understand why the British farming industry should pick up the tab.
"This isn't farmers crying wolf, they fear for their future and for the future of their children.
"There is sheer desperation. People are so, so desperate."
Mr Handley, from Monmouth, said his family farm with an 140-strong herd had seen £50,000 wiped from its profits since last May.
"That's £50,000 that has been committed to other things - trying to make a living and the infrastructure of keeping a dairy herd, which is very expensive," he added.
"Each month we are getting a letter saying 'sorry your price is less'. We are a small family farm, we have had cows for 30 years.
"We have been told we are very good at what we do, we produce Red Tractor products and we are facing selling our cows.
"That's the harsh reality of it."
Mr Handley said there were 24,000 dairy farmers in the UK 15 years ago but that number has now dropped to 10,000.
"If people carry on leaving the industry we will be down to 5,000 in the next five years," Mr Handley added.
"From a consumer point of view that is very, very bad news."
Speaking before the summit, NFU president Meurig Raymond told the BBC the situation had became a "crisis".
"In dairy, many milk producers have seen price cut after price cut," he said.
"It's simply not sustainable for any farmer to continue to produce milk if they're selling it at a loss."