Hundreds of Adecco agency staff working for the British Cattle Movement Service (BCMS) in Cumbria are to be balloted over union recognition by the Public and Commercial Services Union (PCS).

The union alleges that the agency staff are paid on average £3 less an hour than permanent staff working on the same site.

Jody Long, PCS member at BCMS's Cumbria site, says: "We are angry about losing pay when computers crash because we're sent home, about having to use leave to cover bank holidays, and about having to come to work when we're sick because we can't afford to lose pay. These issues and blatant injustices need to be addressed with management when PCS is recognised at the site."

BCMS, which tracks cattle throughout their lifetime in the UK, is part of the Department of Environment, Food and Rural Affairs (Defra).

An Adecco spokesman said: "The BCMS is currently working with Adecco in a review of the current process of regionalised pay rates. Adecco works closely with all clients to ensure that temporary workers are paid the market rate based on local demographics and clients' requirements.

"All Adecco temporary workers are on contracts of employment, which entitle them to holidays, sick pay and a variety of other benefits based on length of service and the business demands of their assignment."

This case is not a first for the industry, but it is a rarity. Tom Hadley director of external relations at the Recruitment and Employment Confederation (REC) says: "It is an interesting case and definitely one we will be keeping a close eye on.

"Temporary workers tend not to unionise. I don't think it will set a precedent for the industry because terms and conditions vary so much from workplace to workplace."

Hadley says a key problem with gaining union recognition is establishing a suitable comparison between temporary workers and permanent staff. "Should temps be compared with an established member of staff who may have better terms and conditions, or compared with a newcomer, where there may not be much difference? Despite reports, a lot of temporary workers receive very competitive pay, and are satisfied."

The ballot takes place on 4 September.