MILK from co-operative dairy farmers makes up just under half the total available to the dairy industry.
The co-operatives then process three-quarters of that milk themselves and broker the rest to the other dairy companies.
Most milk, about 55% of the UK's production, goes straight from farm to dairy companies for processing.
In terms of turnover Arla is the biggest company in the country at £1.76 billion, then Muller Wiseman (£1.5 billion), Dairy Crest (£1.382 billion), First Milk(£0.53 billion) and United Dairy Farmers (£0.418 billion).
Arla is the biggest co-op in terms of milk supply with 2.9 billion litres, then First Milk (1.7 billion) followed by United Dairy Farmers (0.5 billion).
The merger between Arla and Milk Link almost doubled the amount of milk being processed by co-operatives.