An aerial view of the livestock carrier Nada docked at the Timaru Port.

The largest shipment of livestock ever to leave New Zealand remains shrouded in mystery.

While a livestock carrier arrived off Timaru on Tuesday, PrimePort Timaru, livestock brokers and shipping agents refused to discuss the shipment.

MYTCHALL BRANSGROVE/FAIRFAX NZ The Nada waits at sea before docking at the Port of Timaru

The carrier Nada has since docked at the port to begin loading 50,000 sheep and 3000 cattle destined for Mexico for breeding purposes. The number of animals involved supercedes the 35,000 shipped by the Daneb Prima to Mexico in 2007. At the time that was considered the largest shipment ever from New Zealand.

READ MORE:

* Large dairy herd shipment to head to China

* NZ's reputation more important than live exports for slaughter

* Live-for-slaughter exports to end

MYTCHALL BRANSGROVE/FAIRFAX NZ The livestock carrier Nada docked at the Timaru Port.

The ship's arrival was not listed in PrimePort's online shipping list. Independent livestock brokers Peter Walsh and Associates refused to speak on the issue but did not deny they were involved in the shipment. Shipping agent Matt Mayo said he was the agent for the Nada but initially claimed it was a passenger ship before refusing to comment further.

It was not until the Ministry of Primary Industries (MPI) was approached details of the shipment were obtained.

It is understood the animals have been held on Rangitata Island, 50km north of Timaru, for several weeks, in preparation for being transported to the port.

JOHN BISSET/FAIRFAX NZ An aerial view of sheep in holding pattern at Rangitata Island north of Timaru awaiting shipment to Mexico.

New Zealand does not export livestock for slaughter and has not done so since a Customs Export Prohibition Order was put in place in 2007. Livestock can be exported for breeding, but there are strict animal welfare standards in place.

A spokesperson for the MPI said it received an application for the export of around 50,000 sheep and 3000 cattle tor Mexico.

"Strict animal welfare requirements will need to be met before and during each shipment. These include requirements around water, food, space and facilities and having export-approved stockmen and veterinarians with the animals.

"Before the animals are transported they will be inspected at the port by an MPI veterinarian to make sure they are fit to travel and their transport is sufficient."

New Zealand Meat and Related Trade Workers Union Canterbury branch secretary Bill Watts said it was assumed the lambs were being shipped for breeding stock as it was illegal to ship livestock from New Zealand for slaughter.

"Any live sheep shipment is taking work away from the local freezing works and taking money from the local economy.

"Smithfield (meatworks in Timaru) kill 35,000 lambs a week; those sheep equate to over a week's work for those people. It's disappointing these sheep are going out of New Zealand - it's exporting jobs."