Sheep Producers Australia is looking for a new chief executive officer with the departure of Graham Smith after 15 months in the role.
SPA policy director Stephen Crisp will step in as acting CEO.
SPA chairman, Chris Mirams, thanked Mr Smith for his service to the organisation, its members and the wider sheep industry.
Mr Mirams said Mr Smith had been mentoring Mr Crisp for the top tole.
"I think he (Mr Crisp) will get a grip on it quickly, he is a top fellow and knows sheep.
"Graham came to SPA from New Zealand's Federated Farmers with extensive experience in food and agriculture and we thank him for the assistance he has provided to the organisation and the board as the first CEO we appointed," Mr Mirams said.
"He has contributed significantly to SPA's role in the development of Red Meat 2030 and the Red Meat Memorandum of Understanding, live sheep export and a range of policy issues during 2019.
"The SPA Board wishes Graham all the best in his future endeavours."
Sheep Producers Australia reported a hefty $386,812 loss in 2018-19 after a $19,719 profit the previous year.
Mr Smith took up the role with Australia's peak sheep and lamb council in August, 2018, after spending 30 years working in the food and agriculture industries in a number of senior commercial positions, mainly in Australia and NZ.
He joined Sheep Producers as the organisation was transitioning to a company structure with a skills-based board.
Mr Smith was also appointed company secretary on April 18, 2019.