The world's largest livestock carrier docked at Napier Port yesterday before taking 6000 heifers to China - many of them pregnant, but the sailing was unlisted.
Fonterra is shipping the heifers using Ocean Drover, due to depart today, which is not listed in Napier Port's shipping guide.
Port services manager Bruce Lochhead said an unlisted visit was not an unusual request.
"The customer asked to not be listed in the shipping guide, which is their right," he said.
A Fonterra spokesperson said it did not request the visit be unlisted, but was unsure whether the shipping company made the request.
Half of the two-year-old heifers were loaded in Timaru.
Ministry of Primary Industries director of animal and animal products Paul Dansted said an Animal Welfare Export Certificate would only be issued once all animals were loaded and inspected by a vet to ensure travel fitness.
"The health and welfare of the animals is the number one priority for MPI," he said.
A Fonterra spokesperson said animal welfare was "always our paramount concern".
"We have best-in-class systems in place to ensure the wellbeing of our animals prior to, during and after their journey - and we strictly adhere to all of the regulatory requirements for the shipping of livestock," the spokesperson said.
"Our own livestock experts present on the day of loading to supervise the shipment and experienced vets, and animal husbandry experts accompany animals to ensure all possible measures are implemented to maintain animal health and comfort."
The Holstein Friesians received a changed diet "well in advance" before loaded onto "the world's largest, purpose-built livestock carrier, with advanced ventilation, feed and water systems."
The 177m ship can transport 75,000 sheep or 18,000 cattle worldwide.
"Welfare of our animals, both on board the vessel and in quarantine upon arrival in China, is overseen and monitored by experienced veterinarians."
In 2003 thousands of sheep died on their way to the Middle East from New Zealand, resulting in a ban on live sheep exports.
In February two heifers died when 4431 were shipped to China.
SAFE campaigns director Mandy Carter said live shipments were unacceptable despite low death rates. It was a high-stress experience and New Zealand was exporting quality stock to a bleak farming experience, she said.
Animals cannot be exported from New Zealand for slaughter, because of concerns over killing methods, but Ms Carter said all animals exported would eventually be killed and until then suffered unacceptable farming practices.
"There are many more problems than what the death rate is on the actual journey," she said.