Some 50 climate activists from Animal Rebellion occupied the distribution centre of Arla Foods at Aylesbury, England, on Monday.
Arla supplies 10% of UK milk, which equates to 2.7m litres a day. Some 30 protesters locked themselves onto bamboo structures and concrete barricades.
The group claimed it was holding the protest in a call for Arla Foods to transition to plant-based production by 2025, in order to address the impacts of the industry on both the climate and animals.
Animal Rebellion is a movement using civil disobedience to call for a sustainable plant-based food system. It plans to continue the protest at the factory until Arla commits to ending dairy production and finding a just transition for workers.
Arla Foods UK has been contacted for comment.