Better merino sheep in the making
Footrot is costing fine wool farmers $10 million a year in treatment and lost production and a genetic test is being developed to identify more resistant sires.
Within 10 years merino farmers hope to have a footrot-resistant fine wool sheep producing more lambs and feeding on better forages that can compete with crossbreds on many parts of eastern hill country.
The FeetFirst initiative is part of a wider project to lift fine wool sheep numbers and production. Merino farmers are also working with researchers to increase lucerne growth in the high country and possibly add russell lupin to the forage lineup.
The Primary Growth Partnership projects are jointly invested by merino farmers through their Merino Inc group, the New Zealand Merino Company (NZM) and the government.
Within the greater project merino breeders have formed Southern Cross Sheep Ltd and are working to remove footrot from their sheep.
"A lot of them have footrot at home and they have selected sheep with ones that don't get it and have come together to capitalise on that," said NZM production science Manager Dr Mark Ferguson. "Their aim is to be able to compete with crossbreds in many hill country areas particularly in the east coast."
In their third year the merino group had made gains and eventually wanted to produce a fine wool sheep with no wool around the head and legs, stronger feet so they did not get footrot and ability to wean lambs at a 125 per cent to 130 per cent rate.
Ferguson said these sheep would be managed without extra inputs by eventually being resistant to worms and footrot and by being productive.
"That's a 10-year aim, but they are making inroads now and it's just a matter of bulking this up."
Assisting this project will be a simple genetic test close to development which will phase out footrot by selective breeding using naturally resistant sires. The hoof infection rots away the foot of the animal usually between its two toes.
The old footrot test was a single gene marker but the next test - a new genomic breeding value - would measure the association between the genes to work out the likelihood of footrot beng passed on. Among the genes of interest will be those providing sheep with their foot shape, the area between toes and skin thickness.
The eventual test will be broken down to a simple system, probably minus one indicating footrot resistance and positive one indicating susceptibility.
A better understanding of genetic variations is being provided by the Central Progeny Test which began with 40 sires and has increased to 130 this year with another 50 expected to be added next year. The sires range from rams producing ultra fine wool to halfbreds.
Ferguson said the fine wool industry needed to build its genetic links between flocks and understand the variations in meat, wool, footrot and disease traits between them.
He said the sires had produced lambs and this would help to see which of them were more resistant to footrot.
"The real limitation (of footrot) is it confines fine wool growing to the alps and if we had more resistant genotypes out there essentially that would allow us to put fine wool in lower lying areas which have been homes to crossbreds."
The gene knowledge would help breeders and farmers predict footrot resistance from a single DNA sample and overcome confusion about whether sheep had been bred well or fed well. Traditional stockmanship would remain valid, but the test would help farmers pick the best sires for their environment, he said.
More than 3500 DNA samples had been genotyped so far using SNP (single nucleotide polymorphism) chip technology.
Geneticists at the Animal Genetics and Breeding Unit of the University of New England had done initial tests on the dataset to see how accurately a sheep's resistance or susceptibility to footrot could be determined from DNA samples.
Another part of the project was to build a better feeding base for fine wool sheep particularly by grazing more lucerne rather than using it for baleage.
More southern high country farmers had followed the lead of Marlborough hill country farmer Doug Avery. Lucerne iwa being grown widely including at Bog Roy Station and Ida Valley Station after work by Lincoln University Professor Derrick Moot and Dick Arnst on 90 properties.
This is expected to add another 6000 hectares of lucerne growing to the high country.
Researchers are also looking at the potential of russell lupin as a feed. The rapidly growing plant can handle tough environments with soils containing low pH and high aluminium levels.