At the beginning of the International Butchery Exhibition (IFFA) in Frankfurt, activists organized various actions and blockades around the exhibition center on Saturday morning.
Around 40 demonstrators hung up several posters against the leading meat industry trade fair.
Some of them chained themselves to the doors at the entrances to the fair, the police said on Saturday.
"Due to the vastness of the site, there are still opportunities for visitors to enter the fair," said a police spokesman.
A reddish substance was also splattered.
The police were initially unable to say whether it was animal blood or just red paint.
She was on site with emergency services and confirmed that the actions in the morning had been peaceful and without any special incidents.