Submissions on the Dairy Industry Restructuring Act close today.
The diary giant wants an end to the 'open entry' law, which means it has to accept milk from all shareholding farmers in its collection area - while its competitors don't.
Damien O'Connor says dairy farmers have a product that's valuable for 48 hours - and then it becomes worthless.
He says open entry protects farmers, but Fonterra needs to be able to compete.
He says it's New Zealand's biggest company and needs to be supported, not undermined.