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326 Australian Veterinary Journal Volume 82, No 6, June 2004

Two CSIRO Livestock Industries’ researchteams are co-operating to help identifygenes that will fight Australia’s most

destructive gastro intestinal sheep nematodes(worms).

It is hoped the gene findings will lead to newand sustainable parasite control options toimprove the overall health of the national flock.

Supported by Meat and Livestock Australia (MLA) andAustralian Wool Innovation (AWI) through the SheepGenomics Program, the Brisbane and Armidale based teams willuse advanced genetic technologies to target haemonchuscontortus (barbers pole worm)-a blood sucking nematode foundin the abomasum of sheep and trichostrongylus colubrisormis(black scour worm)-an intestinal browser found in theduodenum of sheep.

Project Leader of the Armidale team Dr Ross Windon saidCSIRO Livestock Industries has selectively bred nematoderesistant flocks of sheep to facilitate both projects and bothteams will be using tissues from the same animals. This will helpto determine the expression of genes in worm resistant andsusceptible sheep over the next three years.

“Once we know the genes we need to turn on we canmanipulate the immune response to express the genes and

examine the best way to administer a vaccine, DrWindon said.

“By identifying key genes we can enhance thesheep’s resistance to nematodes by mimickingthe actions of the genes or alternatively if thegenes are involved with susceptibility we canblock those gene products.”

The Brisbane team will use real time PCR toscreen a number of candidate genes known to be involved indisease responsiveness and resistance

Dr Windon’s team will provide the parasitological andimmunological expertise for both projects.

“The aim is to see if there are similar control mechanisms sothat the one mechanism that results from the work couldcontrol both species at the one time,” he said.

“We’ll do a broad scan of a large number of genes anddetermine the number of genes involved in the immuneresponse or even the cascade of immune responses involved inthe rejection of the parasite.”

Gene expressions that are consistently different betweenresistant and susceptible animals will be targeted for furtherstudy. The sheep nematode research may also be used to identifycandidate genes as selection markers for resistance in futuremerino improvement programs.

Sheep nematodes targeted through genomics

Atropicalised meat sheep that looks likea goat could help revolutionise thePacific Island livestock industry.

Originating from the Carribean, theBarbados Black Bellie is well suited to thetropics’ wet, humid conditions and is bredpurely for meat rather than wool.

The Fijian authorities could not initiallyimport the sheep from the Carribean becauseof risks from scrapie and blue tongue.However, after looking further a field, theysoon learnt of a small disbandoned flock of45 animals in California.

According to Commonweath VeterinaryAssociation President Robin Yarrow, his teampurchased the Barbados Black Bellies in thelate 70’s.

His team then quarantined the BarbadosBlack Bellies on a Fijian island for 20 yearsduring which time they cross bred theBarbados Black Bellies with some biggerframed wool sheep and in the processdeveloped a hybrid cross breed that is idealfor production meat.

The visionary Fijian project which hasbeen 20 years in the making, is now anational priority involving six Fijian paraveterinary staff and one chief veterinary

officer to supervise the breeding program.“We now have 8000 of these sheep in Fiji

and we will shortly be sending a smallshipment of 40-50 sheep for breeding toSamoa, said Dr Yarrow.

“We call them hair sheep because that’swhat their coats are. They really look like agoat and you can only see a few stragglypieces of wool on them. But they’re moremeaty and much easier to manage thangoats. We’d like to build the herd up to 200-300,000 but that’s a long way off,” DrYarrow said.

Tonga, Samoa, Vanuatu and the SolomonIslands have all expressed great interest in themeat sheep breeding program and areexpected to take consignments of breedingstock. All of these nations eat a significantamount of imported sheep meat from NewZealand and the project has particularrelevance for the Pacific Islands supportinglarge Hindu populations where people prefer

sheep meat or goat meat to beef due to thecow being sacred to their culture.

According to Dr Yarrow Fiji has trialledwool sheep for over 100 years with limitedsuccess.

“Traditionally the animals are plaguedwith a lot of feet problems and fly strike andit’s like “trying to survive in the tropicswearing a woollen coat,” he said.

Relying upon a quarter of million goats tosupply the bulk of their meat, has also provedproblematic for the Fijians. Goats are notgood grazers, cause erosion, break out offences and often ring bark young trees.

Then there’s the simple practicalities ofIsland living.

“For a lot of the villages in these islandsit’s much easier to handle a ‘hairy’ sheep thana large bovine animal,” says Dr Yarrow.When you have no refrigeration you have toeat the meat within 24 hours or it goes bad,so a smaller animal such as a sheep or goat ismuch easier to deal with.”

With time and application, the newtropicalised meat sheep could give rise to athriving Pacific Island meat productionindustry helping to reduce sheep meatimports and increase income for localfarmers.

‘Hairy sheep’ could spark new industry for Pacific IslandsBy Mark Thornley