At least 1400 dairy workers have walked off the job across Victoria, calling for better pay and working conditions.
The 48-hour industrial action will target large dairy companies such as Saputo, Fonterra, Peters and Lactalis.
Popular brands including Western Star butter, YoPro and Peter's Ice cream are expected to be affected.
The United Workers Union (UWU) labelled the action as the "biggest dairy strike in living memory".
UWU national secretary Tim Kennedy said wages needed to rise for workers to combat the cost-of-living crisis.
"These workers are fighting for safe, secure jobs in regional communities, where almost every dollar they earn goes back into those communities," he said.
"Given the historic nature of the strike across the state consumers can expect a big impact on supply chains and their favourite products."
Workers are calling on companies who had seen milk prices and profits rise, to also increase worker wages.
"These workers are not even asking for a wage increase that keeps them ahead of the current inflation rate," Kennedy said.
"While the dairy industry sees profit increases, these financial gains are not being fairly distributed to the workers.
"Our members are the backbone of this industry, and it's high time profits are shared more fairly."
Gippsland Jersey director Steve Ronalds told Today that there could be some issues with milk supply in supermarkets in the coming weeks.
"It depends how long this action goes for. On this farm we are producing 12,000 litres a day, we are only small farmers. That is potentially going to get tipped down the drain in some of these farms which isn't good," he said.
Although his workers were not striking today, Ronalds said it was a tricky balance but acknowledged larger companies needed to look after staff.
The Victorian Farmers Federation President Emma Germano said there needed to be a wider conversation into the future of supply chains.
"We hope the industrial action is settled as soon as possible," she said.
"It's a balancing act, with farmers, processors, workers and the consumer all competing for a fair price that allows for a sustainable and viable dairy industry.
"Broadly speaking, we need to talk about how standover tactics have a different impact of fresh produce. The issue is more acute because the loss and spoilage has much wider economic and environmental outcomes."
Saputo told 9news.com.au earlier this week, that they were committed to "negotiations to reach an agreement for our valued workers".
"We are focused on collecting and processing every litre of milk possible and are working collaboratively with farmers and industry to ensure we have a home for suppliers' milk during the industrial action," said Gerard Lourey, Saputo's Director of Operations.
Fonterra said it was disappointed that the UWU had encouraged industrial action, but respected the rights of those who chose to strike.
Lactalis said it expected some delays to milk collection but would do everything in its power to ensure the action would not result in farmers having to dump their milk.
Peters has been contacted for comment.
