Nationals senator Barry O'Sullivan has urged Agriculture Minister David Littleproud to review competition law to stamp out collusion in agriculture.
The outspoken Queenslander said not enough had been done to address the issue since an Australian Competition and Consumer Commission investigation into a boycott at a Victorian saleyard in 2015.
It was alleged the buyers boycotted the sale at Barnawartha, in the state's northeast, in protest at the saleyards' practice of pre-sale weighing.
"It was clear that the majority of the nine were involved in a concerted effort not to turn up on that day and impact on the market place," Senator O'Sullivan told an estimates hearing on Thursday.
The ACCC found there was not enough evidence the nine buyers colluded, although they had communicated about the sale.
Senator O'Sullivan said the buyers had offered up "bulls*** on bulls***" excuses over why they snubbed the sale.
"The dog got the homework. One of them said my mother-in-law wasn't well. Flat tyres. Windscreen wipers not working," he said.
He wants Mr Littleproud, a fellow Queensland National Party politician, to consider legislative changes in defining concerted effort or practices in competition law.
"You don't need a cellar or cigars to come together and collude," Senator O'Sullivan said.
He said big players in markets could follow each other's behaviour without obviously documenting their intention to work together.
"All they've got to do is 'I nose what you're doing'," the government senator said, tapping his nose.
Senator O'Sullivan is chairing his final session of estimates as chair of the rural and regional affairs committee after losing a pre-selection battle.
