The department has tried a variety of approaches in trying to get its workforce to agree to a deal, including an unorthodox intervention by Agriculture boss Daryl Quinlivan before a vote in March, with the Departmental Secretary telling workers that a yes-vote was a vote against sickie rorts in the department.

The main workplace union, the CPSU said the latest no-vote showed the government’s approach to bargaining with its own public servants was “ridiculous”.

“Workers in Agriculture and Water Resources have now been forced to vote no four times, while the government’s bargaining policy means management’s hands remain tied so they can’t make the simple and reasonable changes that would result in an acceptable offer,” the CPSU said.

“Just in the past few weeks we’ve seen … similar rejections for the Administrative Appeals Tribunal and National Museum, while workers in two of the Commonwealth’s largest agencies, Human Services and Immigration and Border Force, have voted down agreements by large margins for a third time each.

“It’s just nuts.”

Another workplace union, Professionals Australia, said the department had only itself to blame for the latest rejection after its “appalling” approach to elements of its workforce.

“They should drop their egregious proposals for the veterinary profession,” Mr Smith said.

“Members were appalled by the approach to this critical profession and realised that if they were treated this way they would be next.

“They should consider moving to arbitration by agreement.

“Four votes and they are further away from an agreement than before. It’s time to get an independent third party in to help the parties reach a resolution.”