Unite members at the Molson Coors brewery will vote over industrial action later this month.
Of the 455 workers at the site, 99% are Unite members and the union is predicting a “massive turnout”.
Unite regional officer Rick Coyle told FoodManufacture.co.uk: “I think it will be an overwhelming vote for strike action on a massive, massive turnout. Everybody thinks that. The strength of feeling is overwhelming.
“There’s massive hostility and a sense of disbelief among workers here. There’s a high-speed collision approaching and common sense will have to come to bear soon.”
The two key issues under dispute are proposed cuts to pay – which amount to £9,000 per worker a year, according to Unite – and “radical” changes to shift patterns.
These give employees 30 days annual leave, which leaves 335 days either working, or at home and contactable to come into work at 23 hours’ notice.
Rick Coyle added: “What this new shift system means in reality is that not everyone will be able to have an annual two-week holiday, because you can be rung up and asked to come in, even when you are on leave.
“Under this so-called ‘flexible operating agreement’, you could also be called in for a full night shift with minimum notice. There will be an on-call system, but no financial recognition for being on-call.”
The shift pattern changes will enable the brewery to cut the workforce by 25, according to Unite.
Workers are currently on a 90-day consultation period for the proposals, which ends on June 10.
Coyle said: “Members will be subject to individual consultations after June 10. If agreement isn’t reached they will individually consult with our members with a view to dismissing them and re-engaging them on new terms.
“A settlement looks very unlikely at present because of the intransigent and hardline attitude of the management at this very profitable company, which has benefited greatly from the chancellor’s recent reduction in beer duty.
“At meetings last month in Burton town hall, members voted unanimously for Unite to prepare for a strike ballot, so we are ready for industrial action if there is not a satisfactory outcome.”
Molson Coors also has sites at Alton and Tadcaster, but Coyle said these workers will continue to remain on the same terms and conditions of working.
He said: “There’s massive investment going into Burton and there isn’t any going into the other sites. People can draw their own conclusions from that.
“They’re knocking large parts of the brewery down and rebuilding it. It’s having a massive facelift, there’s a great deal of investment.
“Historically, the company has been a good employer but this is an ideological change – they’re asking themselves what a new brewery would look like and what sort of pay rate a new brewery would have.”
Carling did not respond to requests for comment.