WorkSafe NZ said Riverlands did not call an ambulance, but drove the employee to an after-hours medical centre, where he sat for 40 minutes without any pain relief.
His hand was crushed and lacerated, and he needed surgery and a five-day stay in hospital. He now suffers ongoing pain and acute carpal tunnel syndrome.
Chief Inspector Investigations for WorkSafe NZ Keith Stewart said Riverlands had failed to guard the machine and inadequately training and supervising staff.
"This machine came with a hazard report that specified how placing hands in the rollers was a risk. The rollers remove nails from beef hocks by gripping and ripping nails from the hoof.
"Riverlands' own internal hazard and risk assessments noted that the rotors of the machine were an issue and could cause 'laceration/bruising/crushes'.
"Riverlands' should have eliminated the hazards by guarding the machine and adequately training and supervising all staff. The employee had neither so he now has to live with a life-long injury due to Riverlands' failings."
Riverlands Eltham Limited is an ANZCO Foods Limited processing site.
ANZCO Foods Limited said in statement a review of induction procedures had been carried out since the accident.
"All new starters now go through a comprehensive supervised induction training programme to ensure all training needs have been captured and appropriate training takes place.
The company said there had been a "breakdown in process and communication" when an ambulance wasn't called for the employee.
"We have since ensured that there are clear guidelines in place where it becomes necessary to call an ambulance."