A cardboard heart representing each animal that died in University of Otago teaching and research last year was hung on the building site of its new animal research facility yesterday.
The 11,358 hearts were placed by the New Zealand Anti-Vivisection Society and other animal rights activists early yesterday.
"Each heart represents one animal that was killed by the University of Otago for research, testing and teaching last year," society executive director Tara Jackson said.
The group wants the university to switch the purpose of the $50million building to non-animal-based research.
"We are really concerned by this reaction," Miss Jackson said.
"If animal-based research truly was the best and most advanced research method that the university had access to, why would they feel the need to hide it so quickly?"
A university spokeswoman described the hearts as "graffiti".
A protest against the lab will be held outside the Hercus Building tomorrow morning.
University staff had met the group about the protest.
"The university welcomes ongoing public discussion about balancing the need to enable important medical and scientific advances with the ethical issues around research involving animals," a university spokesman said in a statement.
"The university holds the view that animal-based research is a vital component in such advances.
"All such research undertaken at Otago goes through a strict ethics approval process and is carried out as humanely as possible.
"It should be noted that the university has always explicitly forbidden the testing of [consumer] products on animals, and supports alternatives to animal-based research where these are feasible."