Thousands of laboratory-tested animals have been denied new lives because a government committee has rejected a plea to rehome them instead of euthanise, animal welfare groups say.
Ministry for Primary Industries (MPI) figures showed 40 percent of the 250,000 research animals used in 2015 were euthanised - about 250 animals a day.
Helping You Help Animals (HUHA) founder Carolyn Press-McKenzie said laboratories' resistance to rehoming showed "an antiquated mindset".
"Perhaps laboratories don't want people to know what they are really doing," she said.
HUHA and the New Zealand Anti-Vivisection Society submitted a petition with more than 16,000 signatures to the government last May, calling upon it to ensure animals used in research, testing and teaching were offered up for rehoming once they were no longer needed. The petition was partly inspired by HUHA rescuing 36 beagles from the Valley Animal Research Centre in 2011.
Ms Press-McKenzie said those dogs had been tested for anti-inflammatory medicine, which required their ligaments to be ripped, were later euthanised and then dissected. Most of the saved beagles were rehabilitated and rehomed after entering, she said.
The Primary Production Select Committee said it would not make rehoming mandatory because there was nothing in the law to prevent research groups from already doing so.
The committee said the MPI had also indicated concerns over how volunteer-run organisations could be "sufficiently resourced to house and care for thousands of research animals".
However, rescue centres were well-equipped for the extra animals and there was a broad network of foster carers in New Zealand ready to help, Ms Press-McKenzie said.
"They can go on to be happy and healthy animals," she said.
It was "a missed opportunity" not to ensure animals got another lease on life as they could "enrich" homes and communities, she said.
"A lot of these animals have just been born in the wrong environment and they are killed there."
The most commonly used species in animal research are cattle, mice, fish and sheep, according to the Ministry for Primary Industries. They were mostly used for veterinary research, animal husbandry, teaching and biological research.
Rodents were predominantly used for medical research and testing animal health products.
Cats and dogs made up around 0.6 percent of animals used in research.
In a statement the Ministry for Primary Industries said, along with the National Animal Ethics Advisory Committee, they "encourage organisations using animals in research, testing and teaching to consider re-homing animals where possible, where it is appropriate to the animal".