Peter King has left his role as chief livestock adviser at the National Farmers' Union to take up a new position with 2Sisters, the major poultry processor.
His role at the company would be similar to his position at the NFU, he said.
King has worked for the union since 1999, when he came on board as an economist before becoming the NFU'S chief poultry adviser in 2001.
He carried out that job for four years until switching to the livestock board.
King said that the highlight of his time at the NFU was persuading Asda to withdraw non-farm assured Brazilian beef from its shelves in 1999.
An agricultural economist by training, King completed a degree in agriculture at the University of Newcastle before receiving a Ministry of Agriculture, Fisheries and Food scholarship to study agricultural economics at the University of London.
King will be replaced by NFU Cymru policy adviser Dylan Morgan.