A dairy products plant in Carmarthenshire is to close later this year with the loss of around 200 jobs.
The co-operative only bought the creamery eight months ago
Dairy Farmers of Britain (DFB),which owns Llangadog creamery, said the decision had been based on its poor financial performance.
It is one of the largest employers in the Towy Valley and had been bought by the farming co-operative in 2004.
Chief executive Malcolm Smith said he was "very disappointed" while farmers' leaders said it was "devastating" news.
Union leaders were due to meet management at the firm again on Thursday to discuss redundancy packages for staff.
The creamery at Llangadog processes around 210 million litres of milk a year from farms in west Wales into evaporated milk and rice pudding.
DFB said it will work closely with local employment agencies to help find jobs for creamery employees "both within DFB and the local community".
Mr Smith said: "We are very disappointed to have to make this announcement, which follows a full review of the Llangadog factory's business performance."
There had been an industry-wide consolidation and rationalisation process and he said "we have only taken this difficult decision after having carefully assessed all other possible options".
"Our ultimate responsibility is to our shareholders - the farmer members - and this move is necessary to improve overall business efficiency and safeguard the returns to our members," the chief executive said.
The co-operative runs 60 distribution depots and 10 processing plants across the UK, including one in Cardiff.
The Carmarthenshire plant is expected to close in a few months time.
DFB says its committed to keeping the rest of its operation open
Carwyn Jones, Countryside Minister, recently met the company and said it had "thoroughly explored all the options to try to avoid closure of the Llangadog site".
He said: "I still hope that a buyer can be found for the site and we will, of course, consider any future approach for financial assistance".
The company assured farmers that their milk would be processed elsewhere, but there was concern this could add to costs.
Peter Francis, chairman of the National Farmers' Union in Carmarthenshire said farmers had been hopeful that DFB would "make a go" of the plant when they bought it last August.
The Farmers' Union of Wales said it had been a "bolt from the blue".
The business was sold by Associated Co-operative Creameries last August to DFB, which is the third largest milk processor in the UK.
Plaid Cymru AM Rhodri Glyn Thomas said: "This is disastrous news for the economy of the Towy Valley. I am devastated that our worst fears have been confirmed.
"Two hundred jobs in a village like Llangadog is the equivalent of 2,000 job losses in a large urban area."
Conservative AM Brynle Williams said: ""I very much regret the loss of so many jobs in an industry which is already struggling to survive in the face of a supermarket price war.
"These redundancies will have a major impact on the rural economy in west Wales."
Jenny Randerson, Liberal Democrat AM, said: "This closure sends shockwaves across the dairy industry as a whole.
"The announcement is particularly damaging for Carmarthenshire. The Welsh dairy industry is in deep crisis and needs a fair deal to be rescued."