A Ministry for Primary Industries (MPI) Animal Welfare compliance team then inspected the dairy herd on Erasmus's farm.
An investigation found he had been breaking his cow's tails (115 of the 135 cow herd) over a period of three to four weeks. He hit them with steel pipes and the milking cups in his dairy shed .
The Ministry for Primary Industries said it was the worst case of wilful ill-treatment of animals to ever be brought before a New Zealand court.
MPI Waikato/BOP compliance manager Brendon Mikkelsen said the inspection revealed serious animal welfare issues with cows on the property showing obvious signs of physical injuries and severe distress.
"Clearly the deliberate abuse of the animals happened over a period of time. When our animal welfare inspector visited the property he found cows which were clearly in distress, with painful injuries, broken legs, swollen hocks, weeping lesions, swollen joints and infections and fractured legs."
The state of the animals meant 25 cows had to be euthanased, some immediately.
"It would have taken a fair show of force to inflict those injuries on the animals and to physically break their tails," said Mr Mikkelsen.
Mr Erasmus owns the herd and was the person in charge. He was responsible for the day-to-day dairy farming operation.
His farm has been visited numerous times by MPI animal welfare inspectors between the initial inspection and the court date.
Part of his sentencing is that he will be monitored at three month intervals.
"Persons in charge of animals have a fundamental obligation for the welfare of those animals. The vast majority of persons in charge of animals on farms take their obligations very seriously," Mr Mikkelsen said.
"It was great that we were advised. We always treat any information as confidential through our 0800 number if need be.
"MPI's animal welfare compliance team cannot be everywhere so it is vital farmers, industry, associated on-farm service providers and the public maintain vigilance and report alleged Animal Welfare Act breaches on our hotline 0800 00 83 33.
"This is a rare occasion with most New Zealand farmers treating their livestock respectfully."
Fonterra keeps a close watch
Fonterra director for milk supply Steve Murphy said Fonterra has worked with MPI since February on this issue and paid close attention to ensure the animals were well cared for and were managed by someone approved by MPI.
``At this point, we are still waiting to see the detail of the sentence handed down to Mr Erasmus.
``We would want to be confident that that there will be no repeat of the incidents that led to the prosecution,'' said Mr Murphy.
Fonterra will review case details with MPI and assess what needs to be done to ensure all parties are satisfied the stock are cared for and the farm is well run.
