Direct Action Everywhere NI said they are celebrating a 'small victory' after Cookstown's Karro Food Group took no deliveries of pigs at its factory today (Saturday).
The activists, just over 20 of whom attended the peaceful protest, said their aim was to raise awareness around "the cruelty of animal slaughter", and make people think.
They said they had intended to "comfort the pigs" being delivered as they arrived to be slaughtered, but were told when they arrived that no deliveries would be made.
Instead they stood peacefully by the roadside holding a number of placards carrying messages like "It's not food, it's violence" and "slaughter is never humane".
The protesters claimed their presence had led to a 'shut down' in production but a spokesperson for Karro Food Group said "no production (was) planned for today in any case" when asked if the factory operated every day.
A number of PSNI officers were also dispatched to keep the peace, while Karro Food Group had a number of barricades erected at the factory's main gate.
Clifford Grant, who organised the protest alongside teenager Matthew McKeefry, said people had come from as far as Dublin, Belfast and Donegal to join the picket.
"We are here today to make people aware of what happens inside a place like this," he said.
"When people go into a supermarket and they buy a wee pink packet all nicely packaged up, they don't actually think about the being that has been killed so they can have that.
"I am sure you've heard of cognitive dissidence - people don't think about what happens in here. They are gassed... it's one of the most soul destroying things you will see, a pig being gassed - the panic and the fear and the squeals of them, it's just horrendous.
"They said production has been closed down for the day and as you can see the place has all been barriered up."
A large part of Northern Ireland's economy is based around agriculture, and Mr Grant said he understood that, and that "people want to keep their jobs" but that he is still against it as "it is still exploiting another being".
"There's always other things they can farm and other crops they can grow," he added.
The Cookstown factory, which slaughters and processes around 1.3m pigs each year is now the largest in the UK and feeds not just domestic markets, but those throughout Europe, Asia, the US and Africa.
A Karro Food Group spokesperson said the company adheres to the strict animal welfare schemes - from farm to fork.
"Karro Food Group respects the rights to peaceful protests of both organised groups and individuals." they said.
"Karro is well-known for championing ethical and welfare standards within UK farming and our priority is always the humane treatment of all our animals; indeed it’s at the heart of our operation.
"Karro adheres to strict animal welfare schemes from farm to fork. These include abiding by governance around pig procurement, transportation of live animals, animal handling staff, and monitoring throughout the process.
"As a forward thinking organisation we continue to actively work to further improve all processes throughout our pork supply chain."
Commending the peaceful nature of the protest and Karro's co-operation, PSNI Inspector Danny Kennedy said: "We are here to ensure their right to have a peaceful protest, to make sure nobody interferes with their right to have that peaceful protest.
"We are facilitating it, but we are also here - and we have spoken to them, and they've all been very nice people - to say that we are here to protect the rights of Karro Foods.
"We are just making sure there is no conflict. They have been very co-operative and Karro have been very co-operative and everything has gone very well and the police have no complaints in any shape or form."