The Green Party has criticised the Government over plans to export 50,000 live sheep to Mexico.
Speaking to Radio New Zealand this morning, Green Party co-leader James Shaw said he had some "doubts" as to whether the shipment was being sent for breeding purposes only, but had no evidence the sheep were being sent for slaughter.
"We don't have any evidence that it's for slaughter, but we would want to be seeing some evidence around, what's the ratio of rams to ewes for example because that would give you some kind of indication about whether they were truly for breeding purposes only, or whether some, or all of them, are for slaughter."
Mr Shaw told RNZ it would be a "terrible journey" for the animals on board.
"It is good that MPI have got standards in place and have got vets and so on, and they will be trying to minimise that. But it is pretty unbelievable to think that 50,000 sheep crammed into a boat on a two week journey, that none of them will die from stress, injury, dehydration etc."
Yesterday news broke that a shipment of New Zealand sheep and cattle was on its way to Mexico, sparking concern from animal welfare organisations.
The largest cargo of animals to leave New Zealand - including 50,000 sheep and 3000 cattle - was loaded onto livestock carrier Nada in Timaru yesterday afternoon, and will leave for Mexico later today.
The Ministry for Primary Industries (MPI) approved the export for breeding purposes but Safe for Animals executive director Hans Kriek said the alleged reason was questionable.
The export of live animals for slaughter has been banned in New Zealand since 2003 when 5000 sheep died on an Australian shipment bound for Saudi Arabia.
"We would question whether the animals really are going for breeding purposes as it is an extremely large shipment," Mr Kriek said.
"Even if that is the case these animals are going to suffer and hundreds will likely die."
He said the conditions on board meant many sheep would end up sick or starving to death.
The organisation was also concerned about the animals' eventual slaughter, Mr Kriek said.
However, Prime Minister John Key said strict animal welfare conditions were in place, Radio New Zealand reported.
"The Mexicans have had a huge drought, and so lots of their breeding stock was wiped out, so they have asked us to send these sheep.
"It is kind of a bit of a win-win, because they are coming from parts of the South Island where there have been droughts and so the farmers have been keen to sell those sheep," Mr Key said.
Mr Key said the sheep had to meet all of the conditions outlined by MPI, welfare standards had to be met, and there was a veterinarian on board, who would travel with the sheep for the duration of the journey.
Speaking to Radio New Zealand this morning Federated Farmers meat and fibre chairman reassured the public that all sheep and cattle on board would be treated humanely.
Mr Powdrell said it was an excellent opportunity for New Zealand to help Mexico out.
"We are well aware of the droughts through the American area, you only need to look in America at their cattle herd at the moment they are very low, and Mexico has had the same issues.
"If they need to be re-building their stock, and at the moment we have many farmers in Canterbury who are very happy to take up this opportunity to help themselves ease their situation and help the Mexicans out."
He would not comment as to how many sheep could potentially die on the journey, or how much space the animals would have to graze on the ship.
"We have got to be really careful about getting emotive about the welfare of these animals. I'm quite confident that these sheep can be freighted to Mexico humanely.
"These sheep aren't just taken from a paddock and put on a ship, these sheep have been collected through a quarantine process, they've put through a transition to the feed that they're going to be eating while they're on the ship.
"We can't say there won't be any deaths... we've just got to get away from this talk about wholesale large numbers of animal perishing on this ship."