Westland Dairy's former deputy chair says he'd vote in favour of a Chinese diary giant purchasing the Westland Dairy co-op.

Shareholders are due to vote today on whether to sell the under-performing co-op to Chinese dairy giant, Yili.

Former Westland Dairy deputy chair and mayor Mike Havill told Mike Hosking a no-vote would mean a lot of uncertainties, including financial stress and low pay-outs.

"We don't have too many choices going forward. For the suppliers, they've done it pretty tough financially the last four or five seasons, and some of the company simply hasn't been competitive."

He says a large percentage of shareholders have likely already voted. He notes that foreign ownership's been raised as an issue, but there are not many other options.

"Once the shareholder loyalty gets eroded and the company culture disappears, you're left with a bunch of stainless and an industry that is struggling, and this is seen as a positive step forward from that."

Havill says the current management team failed to deliver on investments making higher value products, like infant formula.

"There were ongoing commissioning issues, quality issues, and basically it hasn't fired. The costs have been front loaded into the company."

The sale is partly conditional on Overseas Investment Office approval.