2 December 2013 Push to eradicate genetic disease within four years

Since its introduction into New Zealand in the early 1990s, the Texel sheep has grown to become one of this country’s key breeds in the national flock, both as a terminal sire and as part of a maternal flock.

“Its high meat yield muscling and hardiness has meant it is a first choice for many sheep farmers,” says Alistair McLeod, Chairman of the New Zealand Texel Breed Committee. “We are always looking at improving and advancing our breed for the commercial sheep farmer, so when we identified a genetic disorder we quickly looked at ways to test for it and eradicate it.”

The genetic disorder in this case is microphthalmia, a recessive genetic condition found in some Texel and Texel-cross (composite) stock which causes lambs to be born blind. When Texel sheep were first introduced into New Zealand at least one of the foundation animals was carrying a defective form of the gene causing microphthalmia. When both parents carry a single form of this gene some 25 per cent of the offspring on average can be born blind.

For a number of years breeders had been working with a test that was imprecise and lead to some breeders making little progress in eradicating the disease. This prompted the Texel industry to approach Lincoln University and its Professor in Animal Breeding and Genetics, Jon Hickford, to develop a better and more accurate test for the genetic disorder.  Professor Hickford took up the challenge and soon discovered that some German scientists had already sequenced the defective gene and found the fault. Consequently, with some smart work from his team, he had an accurate test available to the industry within two months.

“It really shows the advantage of all countries working openly together on sheep science and that gene development need not cost a lot if we can all work together,” says Professor Hickford.

Mr McLeod said that after years of working with gene technology that simply didn't meet their requirements it was surprising how easy the solution was. “We then went back to Professor Hickford and asked for a price for gene testing that would encourage most of our breeders to test for the disorder. He came back to us with a price which was between one third and one quarter what we had been paying,” he said.

Professor Hickford says that this gene test “is not about generating wealth, but instead is an ‘industry good’ initiative provided by Lincoln University to the Texel breeders at cost because of the importance of eradicating microphthalmia from the stud stock and minimising its effect on the national flock.”

Mr McLeod advises all commercial farmers buying Texel or Texel-cross rams to talk to their breeder and make sure that they are either going to test, or have tested, for the faulty form of the gene. “They need to be confident that they are not passing on the disease,” he said. “Our breeders are working hard to eradicate this disease from our industry and are hopeful that this will occur within three to four years.

“We are now working with all our society members and have introduced an accreditation scheme for our members so that we can be free of this disease,” he said.

“We already have very robust sheep, but this approach will make them even better,” he said.

Jon Hickford confirms that this year they have had two commercial farmers who have used composite Texel rams for a number of years who have now identified microphthalmia affected lambs. “This means both ewes and rams are carriers on these properties,” he said. In both cases he advised the farmers to go back to their ram breeders and “insure they have a program in place to eradicate the faulty gene.”