In 2019, the University of Otago bred more than 67,000 animals that it then killed without using for any scientific purpose.
That year, the university was responsible for half of all the animals killed in New Zealand that had been bred but not used for research, testing and teaching (RTT) purposes.
University research and enterprise deputy vice-chancellor Richard Blaikie has defended the institution's record and has said it was working to reduce the number.
New Zealand Anti-Vivisection Society director Tara Jackson has called the university's care of animals "very sloppy" and "incredibly disappointing".
Yesterday, the Ministry for Primary Industries released the latest national figures for animals used in RTT. For the first time, MPI also released the number of animals bred for scientific purposes but killed without being used.
They show 131 organisations, including seven universities, used a combined total of 315,574 animals for RTT in 2019.
An additional 136,679 animals were killed after being bred for RTT but not used.
In 2019, the university, which this week opened its new $50 million animal research facility in Dunedin, used 35,076 animals for scientific purposes across its Dunedin, Christchurch and Wellington campuses.
A further 67,641 animals were bred and killed without being used.
Of the Otago animals used for RTT, 57 per cent were fish, 19 per cent were mice, 13 per cent were sheep and 7 per cent were rats.
Animals euthanised by the university without being used were 44,308 mice, 11,149 fish, 10,992 rats, 1191 guinea pigs and one sheep.
Otago is one of seven universities and 124 other organisations and companies included in the MPI animal use figures.
Nationally, almost a third of all animals bred for RTT purposes were killed without being used. At Otago, the percentage was more than double that, 65.9 per cent.
Otago accounted for 23 per cent (102,717) of all animals bred for RTT use in New Zealand and for half (67,641) of all animals bred for RTT but killed without being used.
Blaikie, who oversees the university's research, said the need to study animals with specific genes accounted for a portion of the "not used" figure.
"If a scientist is studying a certain gene, it will not be present in all the offspring — the pups without the gene are not needed for the project.
"To mitigate this, we do targeted and on-demand breeding, to avoid unwanted and unwarranted production of offspring.
"We also must note that we do not have large-scale commercial suppliers of laboratory animals in New Zealand from which we can order our animals on demand.
"We need to hold and maintain our own breeding colonies, which contribute significantly to the number of animals we report under the new 'bred but not used for research category'."
Jackson was disappointed with the national figures.
"It shows that ... no real progress has been made and as a result animals are continuing to suffer in labs in New Zealand."
She described the university's figures as "a sad indicator of how careless researchers can be with animals' lives".