The Ministry of Primary Industries said Covid-19 had impacted the investigation and it was essential the chicken death inquiry was thorough.
But Marcelo Rodriguez Ferrere said the Ministry of Primary Industries (MPI) had nowhere near enough inspectors.
"In some ways it makes sense that it would be a lengthy investigation. It really is such an incredibly large amount of deaths," the University of Otago lecturer told the Herald.
"That said, 14 months is an insanity. For an investigation to take that long is really just far too long. It's entirely due to resource pressures."
Rodriguez Ferrere, an animal law expert, said the incident northwest of Auckland was "the biggest mass death" in New Zealand history.
It's understood one or more disasters possibly including a power cut, ventilation failure, backup generator failure, and alarm failure may have caused the deaths.
Rodriguez Ferrere said New Zealand had at least 100 million production animals but barely two dozen dedicated inspectors.
Meka Whaitiri says she'd love to have more inspectors but resourcing and budget decisions have to be made within the context of the country's response to Covid-19. Photo / Mark Mitchell
An Official Information Act response from MPI to Rodriguez Ferrere at the end of August showed the ministry had 27 full-time dedicated animal welfare Inspectors.
Another 19 compliance investigations staff held animal welfare warrants, enabling investigations under the Animal Welfare Act.
"Prior to Covid, I heard from sources there were going to be big increases to their inspectorate levels," Rodriguez Ferrere said.
But he said that never eventuated and the number of inspectors had basically stagnated for years.
Meka Whaitiri, Associate Minister of Agriculture responsible for Animal Welfare, said in an ideal world she would have more inspectors.
"Of course I'd like to see more. The reality is, we're dealing with Covid issues and making sure we've got resources. It's a balance."
National Party MP and agriculture spokesman David Bennett says the duration of the chicken deaths investigation is concerning. Photo / Christine Cornege
Whaitiri said most farmers and primary sector producers were responsible and keen to abide by welfare standards.
She said meat and dairy sector members she'd met recently had voiced desires New Zealand had a reputation for upholding high standards of animal welfare.
Whaitiri said future budgets could provide more money for inspectors, and she viewed animal welfare as a key Government priority in the primary sector.
He said concerns about under-resourced inspectors hadn't been raised with him but some MPI staff at the border could be possibly redeployed if staffing was an issue.
Bennett said with international flights massively down on pre-pandemic levels, MPI could mull re-routing staff to investigations.
MPI this week said two investigators were assigned to the Helensville case but the ministry was also working with an independent expert.
"The number of people on any investigation will vary according to the stage and scale of the case," an MPI spokeswoman said.
She said Covid-19 restrictions caused delays last year.
"While we acknowledge that the case has taken some time to investigate, we need to ensure the matter is thoroughly investigated."
