About 150 protesters marched through Hull city centre on Saturday to voice their objections to the work of B&K Universal, a company breeding beagle dogs and rodents for use in animal experiments.
Members of the Northern Animal Rights Network (NARN) carried banners claiming the firm was involved in the "torture" of animals.
NARN spokesman Luke Steele said: "We want to raise awareness about this company. We believe what they are doing is immoral and wrong.
"There are around 400 beagles there at any one time and their mothers are just used to breed litter after litter. The puppies are sent across the UK and to Europe.
"They are then tortured in experiments which do not need to be carried out. We want to close them down. "
Police have created a one-mile exclusion zone around the company's premises in Grimston, near Aldborough, East Yorkshire, to bar protesters from the site. Officers filmed demonstrators at the meeting, which was carried off peacefully.
Veteran activist Mel Broughton, of Speak, who addressed the crowd in Queen Victoria Square, said campaigners had the industry and politicians on the back foot. He said: "The Government is running scared on this because we are winning the argument and we have huge public support. It doesn't matter if there's a one-mile exclusion or 10 miles, we will not stop until this practice is stopped.
"Research on animals is unethical and unscientific. It does not benefit people.
"These animals suffer and they suffer terribly and we cannot stand by and let that happen. The rights of animals must be considered alongside the rights of people."
Residents living near the firm say they sometimes feel troubled by the sound of the dogs barking and yelping. But others say it is bringing valuable jobs to the area.
A spokeswoman for B&K Universal has said that animals have a crucial role to play in medicine and that animal testing still receives strong support among the medical profession and the public.
She also claimed 91 per cent of doctors had expressed support for the continuing use of animals in medicine.
A spokeswoman for the Research Defence Society, which represents scientists involved in animal testing, has also defended the company, saying animals have a "vital" role to play in research.
simon.bristow@ypn.co.uk