Workers at Bernard Matthews poultry factories could strike over plans to extend their working week from four to five days.
The firm is known for its fresh and frozen turkey
Their union says staff are also unhappy with a pay rise offer of 2.6%.
More than 70 workers gathered in protest before the Tuesday morning shift at Great Witchingham in Norfolk.
But the company said: "There is nothing to say; there is no action. Discussions with the workers continue in their normal democratic way."
Strike ballot sought
Bernard Matthews Foods wants its new working week arrangements in place within six weeks.
However, a spokesman for the Transport and General Workers Union (TGWU) told BBC Look East it was preparing to hold a strike ballot among its 1,700 members at the plant.
The company employs more than 4,000 people at plants in Norfolk and Suffolk.
Operations in Hungary, Germany and New Zealand bring its worldwide labour force to more than 6,000.
Production was not affected by the protest.