THE world's largest meat processor, JBS Swift, now has a representative on the Meat and Livestock Australia board.
Mr Mars joins a more streamlined board, which has reduced its number of directors from nine to eight.
However, Australian Beef Association chairman Brad Bellinger, a critic of Mr Mars' appointment, said the company now "had a number of meat processors on the board".
"His appointment means that a representative of the world's largest processor, JBS Swift, now sits on the board," Mr Bellinger said.
"JBS are not only the biggest processors in the country, but they also have more votes than anyone else ... and can effectively control the outcome."
Mr Mars said he was "pleased and honoured" to be elected to the role.
"I don't there is a conflict of interest. There is policy that covers any issues with board members and a conflict of interest," Mr Mars said.
"I have been in the industry for 30 years and hope to bring a lot of that experience to the board."
Supporters of Mr Mars' appointment believe his experience in international market places and knowledge across the whole industry will be invaluable.
Former Cattle Council president and Gippsland beef producer Bill Bray said Mr Mars would "add value to the MLA board with his extensive knowledge across the industry".
MLA board director and sheep processor Peter Trefort earned re-election at the meeting, while first-time nominee, CSIRO livestock industry deputy chief of business developments Greg Harper, was also appointed to the board.
Mr Mars, another first-time nominee, received more than 81 per cent of votes, while Dr Harper earned 88 per cent and Mr Trefort an overwhelming 96 per cent.
Beef producers also used the meeting to vote to retain the $5 cattle transaction levy.
More than 72 per cent of votes were cast in favour of retaining the $5 levy - rather than cutting it to $3.50.
"It is pleasing to receive such strong support from the industry and I can assure producers that MLA remains committed to continuing to work hard to deliver a return on their investment," MLA chairman Don Heatley said.
The vote was the culmination of a 12-month process including the Committees review and a six-month campaign to create awareness among producers and encourage them to participate.