Sheep farmers Colleen Fenemor and John Coley are celebrating the birth of quintuplets on their Brunswick farm.
Their Romney ewe had previously given birth to quadruplets and Fenemor thought there might be four this time but the mother surprised her by producing a fifth lamb.
"They were all a good size too and they are doing well.
"I've taken two of them to be bottle fed because sheep only have two teats."
Fenemor said the births were trouble free and jested that the mother named her lambs as they were born.
"She was calling them Ma-a-a-rtha and Ba-a-a-bara," she laughed.
Whanganui veterinarian Peter Murray said five lambs is very unusual, especially for a Romney sheep.
"I'm amazed that they are all healthy too.
"I have delivered five lambs in a single birth when I worked in Wales but they didn't all make it."
Murray said some breeds of sheep are more likely to have multiple births but it is unusual for all the lambs to survive.
He said farmers like to know if their ewes are likely to produce more than one lamb so they can provide more feed.
"A scanning tool will show that there is more than one but it doesn't show how many."
There is a more sophisticated tool that will detect more embryos but Murray said it is difficult when vets might be scanning up to 4000 ewes on some farms and it is more costly for farmers.
Colleen Fenemor said the ram that sired the lambs is a Poll Dorset known for their superior genetics and high lambing percentages.