A total of 57,226 animals were killed by the university without being tested on in 2020, data obtained by the New Zealand Anti-Vivisection Society under the Official Information Act shows.
Society director Tara Jackson criticised the numbers, which constituted nearly 40% of the total number of animals bred, not used and killed for science, nationwide.
However, university research and enterprise deputy vice-chancellor Richard Blaikie said Otago operated one of the largest biomedical research facilities in the country, in which projects were subject to strict ethical approval.
"Research undertaken at the University of Otago has contributed directly to significant medical breakthroughs in many chronic and deadly diseases and conditions, including heart disease, infertility, diabetes and cancer," he said.
By comparison, the University of Auckland killed 49,537 animals bred for research, testing and teaching (RTT) without using them in 2020.
The number was 3124 at Victoria University of Wellington and 1212 at the University of Canterbury, while other universities numbered less than 50.
Also in 2020, the University of Otago used 21,599 animals for RTT, of which 16,186 were killed.
The University of Auckland used 6691 and killed 6433, while Massey University used 47,115 and killed 21,064.
Data released by the Ministry of Primary Industries earlier this year showed that universities accounted for 41.1% of animal RTT usage in 2020.
Miss Jackson criticised the university’s use of animal testing as cruel and sometimes ineffective due to differences between mice and humans.
She called on the university to make improvements.
"The University of Otago needs to start investing in non-animal based methods right away," she said.
Prof Blaikie said the lack of any large-scale commercial suppliers of laboratory animals meant the university needed to maintain its own breeding colonies.
Animals used in an experiment needed to be of the same age and condition, and often in a litter of animals only some could be used, he said.
"Researchers will try their very best to make use of the remaining animals, but this is not always possible."
Surplus culled animals were sent to high school science classes to use for dissection, or wildlife organisations to use as a food source.
The number of animals killed without use at the University of Otago in 2020 had dropped from the higher figure of 67,641 in 2019.
Last year the university opened the Eccles Building, a $50 million animal research facility.
Prof Blaikie did not speculate on what more recent data might show, but said the university was seeking ways to reduce and refine use.
"In the past year, Otago has established a more formal process for the sharing of tissue, and reusing animals for more than one research project.
"We are refining technical methods so we can obtain more information from fewer animals."
Animal research was only carried out when essential.
The University of Otago was an inaugural signatory to the Openness Agreement on Animal research and Teaching in New Zealand, he said.
"The agreement expressed the University of Otago’s commitment to provide information to the public, and tangata whenua in particular, so that they can be well- informed about research using animals."
Miss Jackson said there was a difference between being open and being progressive, and the agreement did not address any of the society’s concerns.
