The moving sculpture by the graffiti artist, which is designed to highlight the issue of animals being farmed for their meat, depicts a truck full of shrieking cuddly animals being taken to slaughter.
Baffled music fans looked on as the vehicle was seen travelling across the fields of Worthy Farm - where 450 dairy cattle are usually grazed when the festival is not on .
Asked to comment on the artwork, farmer and festival organiser Michael Eavis said: “Is it some kind of animal rights thing?
"I'm not sure about it. Our cows are actually very happy, they have the highest milk yield in the county."
The piece was first seen on the streets of Manhattan during Banksy's month-long New York residency last year and was subsequently impounded by police.
Today marks the first time it has been seen in the UK, with the new version using a local Somerset truck with "25 per cent more added terror", according to local boy Banksy, who is based in Bristol.
Additional reporting by Press Association
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