Nearly 250 jobs are under threat in Cambridgeshire after supermarket milk supplier Dairy Crest announced plans to close two dairies.
The proposed closures include the site at Fenstanton and a glass bottling dairy at Aintree, where 220 people work.
Dairy Crest said a recent £75 million investment enabled it to transfer work to its three dairies at Severnside, Chadwell Heath and Foston in Derbyshire.
The company said it's battling an "extremely challenging" market for liquid milk and the plans, which are subject to staff consultation, would help it reduce costs and sustain profitability.
Dairy Crest, which employs 4,000 people in its dairies business and 6,000 people overall, also announced that its current contract to supply liquid milk to Tesco will not be renewed in July.
Around 3% of the company's liquid milk sales are made to Tesco and Dairy Crest said the loss of the contract was not a factor in the decision to close the two dairies later this year.
The demise of the Aintree site reflects the fall in sales of milk in glass bottles as residential trade continues to decline and customers increasingly opt for plastic bottles and milk bags.
Dairy Crest also has a food division which makes leading brands such as Cathedral City, Country Life and Clover.
Chief executive Mark Allen said the dairy closures would protect the future of the dairies side of the business.
He added: "The decision to consult on the closure of our Aintree and Fenstanton facilities has not been taken lightly, but we believe that this proposed restructuring of our dairies business is the right decision for the long term."