Supermarket giant Coles has hit back at a scathing attack by Liberal Democrat David Leyonhjelm, questioning whether he's misused his position as a senator.
Senator Leyonhjelm lashed out in parliament on Tuesday labelling the supermarket "stupid and culpable" over its decision to prohibit its pork suppliers from using a vaccine on male piglets that blocks the production of hormones at puberty.
Coles' policy is that its pork suppliers not use the vaccine Improvac on their stock.
The supermarket's government and industry relations manager Vicki Bon wrote to Senator Leyonhjelm in March, expressing her disappointment at his threat to raise the issue in parliament and the media if he did not receive a reasonable response.
"Some would suggest that making such threats is a questionable use of your position," she wrote.
The letter notes the maker of Improvac is pharmaceutical giant Pfizer - a client of Senator Leyonhjelm's consultancy firm Baron Strategic Services.
Senator Leyonhjelm says Pfizer is no longer involved in animal health and the company that now sells Improvac, Zoetis, is not a client of his firm.
It has been in the past, as have most animal health companies.
"That's a reflection of the fact that I'm a vet and a businessman and I have particular knowledge of the animal health industry," he told AAP.
"That's why I'm in a position where I can criticise Coles because I actually know what I'm talking about."
Zoetis was a Pfizer subsidiary but is now an independent company.
Senator Leyonhjelm accused the supermarket of trying to attack his credibility instead of dealing with the issue he raised.
"If you can't justify your actions, what do you do? Criticise the person who's making the criticisms."
Senator Leyonhjelm says male pigs became aggressive when they reach puberty and also develop boar taint, which creates an unpleasant taste some consumers find "utterly offensive".
The problem can be solved by castrating the pigs before they reach puberty, but that creates animal welfare issues and also has an economic impact for the farmers because it impacts on the growth of the pig.
If the pig farmers were allowed to use the vaccine, the pigs would not fight, would not develop a yucky taste and would grow to a good size.
"It's so they can say to consumers 'we don't sell pork that contains things' - things it knows nothing about," Senator Leyonhjelm told parliament.
"It feeds on ignorance and bigotry about agriculture."
As a result, Coles suppliers are forced to castrate pigs, slaughter them too early or risk losing consumers because of the bad taste, he says.
"Coles does not actually care about pig welfare or the pig industry or its own consumers, it just wants to be able to tell a nonsense story to gullible consumers.
"If it isn't fixed, I'll have a lot more to say about it in future."
Coles insists it does not require its suppliers to castrate male pigs, and does not advocate surgical castration.
It says its customers want products that are naturally produced and that its standards were agreed to after extensive consultation with Australian Pork Limited.
