It might sound like something straight out of the 2006 horror comedy Black Sheep, but woolly mutants are leading our scientists toward intriguing discoveries - and innovative new products.
What are called Felting Lustre mutant sheep could also help us better understand what makes our own hair curly or straight.
The rare and quirky animals, which share the share the naturally-occurring trait of straight wool, have been studied by AgResearch scientists since 2011, when a lamb with an unusual coat was brought to the attention of staff involved in wool research.
Its appearance was so unusual that the lamb was initially thought to be a cross between a sheep and a goat, partly because its straight lustrous coat was reminiscent of an Angora goat.
Genetic testing showed it was 100 per cent sheep and its coat was the result of natural mutation.
"As a result, we started trying to locate more of these rare sheep, so we could study what makes them different and how proteins in the wool affect the fibres," said AgResearch scientist Jeff Plowman.
Lustre mutants grow wool that resembles that from the "lustre breeds" like the English Leicester, Border Leicester or Lincoln and to some degree the Finnish Landrace or the mohair from an Angora goat.
With these mutant sheep, scientists could tease out key differences between twin lambs to reveal how one had straight wool and the other crimped, or how one animal was able to transform from straight to crimped wool over time.
"This can then be applied to our understanding of the differences in human hair," Plowman said.
"It's an opportunity we would never have been able to get with human subjects."
With help from farmers, scientists have been able to track down more of the sheep and reveal intriguing changes in wool structure and properties that can be tied into specific protein changes.
"In some cases, the mutant sheep undergo a transformation where the straight wool suddenly switches to become crimpy as they mature."
The curvature and diameter of the wool fibre were important properties in controlling performance in textiles and other products.
While softness, strength and felting were all affected, the ability to control these properties remained limited because diameter and curvature were normally highly linked in sheep - low diameter meant high curvature and vice versa.
"These mutant sheep are exciting because they break the mould and give us a shot at what controls each property independently, something impossible with normal sheep," Plowman said.
"People keep asking us if we are trying to breed the mutants themselves, but the situation is more complex than that.
"The mutant sheep, as lambs, have the same problem that Angora goat kids have - which is that they are a bit delicate, and probably not suitable for most New Zealand farms."
Plowman and his colleagues now want to use what they learn to add value to New Zealand's mainstream sheep flocks.
"The protein differences between the mutant sheep and semi-lustrous breeds suggest that it may be possible to breed wool with controlled levels of lustre, or crimp, independent of diameter and hence produce new wool products which allow for different market opportunities."
Our mutant animals
• Natural mutations have played an important role in New Zealand's farming history. Many years ago, a mutation in Romney sheep produced the Drysdale, a very hairy sheep with horns that became a significant breed, though numbers have declined.
• The identification by AgResearch scientists of prolificacy gene mutation, the Inverdale gene, and the subsequent development of the genetic test for it has given farmers a new option when making reproduction management decisions.
• While not all mutations become so useful or productive, they were always helpful in improving understanding of normal animals.