The animal advocacy organisation SAFE has renewed its call for a ban on all live animal exports.
Of the 45,000 sheep and more than 3000 cattle left Timaru for Mexico last month, 191 sheep and one cow died during the 15 day voyage.
"One hundred and ninety two animals have died and it begs the question, how many more will die on the next stage of their journey?" said SAFE's executive director Hans Kriek.
He said the sheep are being transported by truck for 1000 kilometres in 30-degree temperatures to a farm near Mexico City from where they will be distributed to smaller farms.
Although the shipment is purportedly for breeding purposes rather than for slaughter, which is illegal, SAFE said this latest shipment ignored the spirit of the ban on live export.
Hans Kriek said the animals will still eventually be slaughtered in Mexico after they were no longer required for breeding, most likely in conditions that would be deemed cruel and illegal in this country.
"We are deeply concerned about what will happen to these animals next ...the journey will have been both terrifying and stressful for the sheep especially as they are already nervous animals by nature. New Zealand has effectively washed its hands of them and has absolutely no control over their treatment now".
He said SAFE is again calling for a ban on all live exports, for breeding or slaughter
The Ministry for Primary industries said "nothing unexpected" happened in terms of the animals' health and welfare during the voyage. And it said the sheep had a 10 to 12 percent weight gain during the voyage.
MPI's Director Animal and Animal Products Matthew Stone said the exact cause of the deaths was not yet known but MPI would receive a detailed voyage report by mid-July from the exporter, which will include information from the veterinarian who travelled with the shipment.
Mexican authorities oversaw the completion of the vessel's disembarkation process.