Around 3,500 British farmers are taking part a three-day strike in protest at the low prices paid by retailers for their goods, organisers have said.
Plans to dry the withheld milk for charitable donations fell through
Milk, meat and vegetables are among the goods being withheld to put pressure on retailers to ensure producers "get a substantial return for their product".
Campaign group Farmers for Action, which has organised the stoppage, said peaceful protests would also be held.
Supermarkets said stocks had not been affected by the strike so far.
Organisers said they expected the action would grow over the three days.
Farmers have been disposing of gallons of milk and in some cases giving perishable produce to charitable causes, said FFA.
Campaigners warned more protests were likely before Christmas.
The group said dairy farmers were being paid 17p a litre for milk, compared with a price of 27p in 1995.
It also warned consumers to shop early in case supplies of some items run short across the country.
David Chapman, a dairy farmer from Henley-in-Arden, Warwickshire, said he is taking around half the milk they produced to spread it over the fields, costing him about £600 to £700 over the three days.
"When the milk doesn't arrive at the supermarkets they might begin to realise that it is produced by a farmer, on a farm, and it's got to come through a dairy to them - it doesn't come from a factory."
He said the price they were receiving for milk had dropped in the last two years.
"We are now at the cost of production, and there is just no way we can go on and make a profit," he told the BBC.
Major supermarket chains said they had been unaffected by the protest so far.
Asda said it had a direct relationship with 650 farmers - meaning it had not been hit by the protest.
Tesco said it wanted to work with its suppliers to create sustainable relationships with farmers.
The National Farmers' Union is not supporting the action.
A spokesman said: "The NFU understands the frustration many farmers and growers have concerning the price pressures involved in supplying to retail customers.
But, the spokesman added, to remove food from the market would not achieve a more sustainable price and it could not condone farmers breaking contracts.
Strike organisers had hoped a Wiltshire dairy would dry much of the withheld milk so it could be donated to earthquake victims in South Asia, said the FFA, but the plant is shut for maintenance.