Workers in Dairy Crest's cheese, yoghurt and dairy products divisions, as well as company drivers, have voted seven-to-one in favour of a full strike ballot, according to the Transport and General Workers Union (T&G).
A strike has been provisionally pencilled in for 6 April.
The action could cause serious disruption to supplies, albeit short-term, if workers vote yes. T&G represents half of Dairy Crest's 2,000 staff, while other unions Usdaw and amicus also pledged their support.
"Home deliveries as well as supplies to small shops, supermarkets and food processors would be affected," said a T&G spokesperson.
Dairy Crest staff were angry at the firm's proposal to close its final salary pension scheme to new entrants after 6 April this year.
The group, one of Britain's biggest dairy processors and owning successful brands like Cathedral City cheese and St Ivel, said its pension deficit has risen to £652m.
The firm has struggled to maintain profits recently due to soaring input costs and supermarket price pressure.
T&G have, however, disputed the £652m pension deficit figure, and a spokesperson said the union was suspicious about why the deficit had doubled in around three years.
T&G wants Dairy Crest to delay the reform until union officials have properly examined the figures. "Until a short time ago the firm said its scheme was in a relatively healthy position, now they're saying it's in a massive deficit. We want to judge that."
A number of British companies, and even the government, have had problems maintaining workers' pension funds due to stock market mishaps and the sheer strain of the country containing more and more people over retirement age.
RHM, which owns bread brands Hovis and Mother's Pride as well as Mr. Kipling cakes, last year announced changes to its pension scheme to reduce a £525m fund deficit.
Britain's 2001 census showed for the first time that the country had more people aged over 60 than under 16. About a sixth of the UK's 60m population was in retirement age.
The UK government last year launched a flat-fee charge on companies' pension funds to help pay for the Pensions Protection Fund (PPF), which it set up in 2004 after many final salary pension schemes collapsed. The PPF was designed as a safety net against a loss of retirement savings, but only for employees on final salary/defined benefit schemes.