He said the cows from the second farm had stayed on the first farm over winter and were sent back just a week before "this all set loose".
"The rest of the stock are fine and calving at the moment."
He was just trying to cope with it now, he said.
"I've got no choice. I can't turn the clock back. (We'll) isolate those animals and kill them and probably start again."
A community meeting was held at Glenavy on Friday to keep farmers informed and another meeting about the outbreak would be held at 11am tomorrow across the Waitaki River at the Papakaio Community Hall, at the corner of Papakaio Rd and Cameron Rd.
The statement from MPI said it was continuing sampling and testing for the disease on all farms in the enterprise, as well as neighbouring farms and results were expected by the end of the week.
All Van Leeuwen farms were under legal controls restricting the movement of risk goods on and off the properties.
Cattle can only move between the other farms in the enterprise and no movement of stock is allowed to farms outside the group.
So far 25 cows had been euthanised, an MPI spokeswoman said.
The carcasses had been sent to a pet food manufacturer.
There was no risk to pets from consuming the meat, she said.
The ministry was satisfied the containment measures in place were sufficient to control any spread of the disease from the properties involved.
Other farmers in the area could be assured that the most likely way for a farm outside the Van Leeuwen Group to become infected would be the introduction of animals from the group.
With all the farms in lockdown, this could not happen.
MPI was tracing earlier movements of animals from the Van Leeuwen Dairy Group farms to and from properties outside the group and was conducting sampling and testing for the disease on these farms as a matter of priority.
The ministry was also prioritising surveillance testing on farms neighbouring the Van Leeuwen Dairy Group farms to ascertain if the disease had previously spread in the local area.
Who are the van Leeuwens?
• The Van Leeuwen Dairy Group is one of the biggest dairy farming operations in the Waimate area.
• Last week, owners Aad and Wilma van Leeuwen were on the National Business Review's 2017 Rich List with estimated wealth of $60million, and have an enormous robotic milking operation - the largest in the world of its type at 23,000sq m.
• The two arrived in New Zealand from Holland in the early 1990s.
• The South Canterbury group has 12 holdings and 12,000 dairy cows with 24 Lely robots in three barns of 500 cows each.
• The Van Leeuwens' barn supplies Oceania Dairy, a dairy plant operating in South Canterbury.
• The Van Leeuwens were founding shareholders of Oceania Dairy business before its sale to Yili.
- Otago Daily Times