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Research Identifies Gene Variant Responsible For Scrapie Susceptibility In Dairy Goats

on August 12 | in Ag News | by | with No Comments

By Lilian Schaer for AgInnovation Ontario

Live goats can now be tested for scrapie susceptibility and resistance thanks to newly completed genetic research by Dr. Bradley White, a biology professor at Trent University.

Scrapie is a slow-moving but fatal degenerative central nervous system disease in sheep and goats that is related to Bovine Spongiform Encephalopathy (BSE) in cattle and Chronic Wasting Disease in deer.

Currently, testing for the scrapie disease in goats is only possible on dead animals and no treatment or vaccine is available. The disease can be spread by positive animals that don’t show any symptoms of the disease, and all goats on farms where scrapie is found are destroyed.

After the detection of the disease in two large Ontario goat herds in 2014, White, in collaboration with Dr. Gordon Mitchell of the Canadian Food Inspection Agency (CFIA), discovered the alleles or different forms of genes in goats that are associated with an animal’s resistance or susceptibility to scrapie.

And as a result of this development, Ontario Goat is now working with Trent University and the Centre of Excellence for Goat Research and Innovation to genotype 1,500 animals in various goat breeds and herds for resistance and sensitivity to the disease.

“We’re short of good genetic information on individual animals across the province so we are working to collect that kind of information from many farms. It is critical if we are to use the new genomic technology,” White says. “One of the things this is going to do for us is allowing genome-wide selection of many genes at once so we don’t select one characteristic at the expense of others.”

White adds that the genotype testing doesn’t establish whether or not an animal actually has scrapie, but if its genes indicate it could be predisposed to getting it. One of the two scrapie positive herds identified in 2014 had 182 highly susceptible, 125 weakly susceptible and 24 scrapie resistant animals before exposure to the disease.

Post-mortem testing revealed that 64 of the highly susceptible animals and only two of the weakly susceptible goats were found to be positive for scrapie. None of the animals with resistant genotypes had the disease.

“This lets you look at your relative risk. If you have a herd with a high proportion of highly susceptible animals, you know they have a high risk of getting the disease if they are exposed to it,” White says, adding that the prion protein that causes scrapie can survive in the barn or the soil for quite some time.

For farmers, White’s discovery could ultimately result in breeding strategies to build herds of scrapie resistant goats, limiting the financial risk an outbreak poses to both individual farmers and the Ontario goat industry as a whole.

It could also lead to increased use of genomics for selection in the goat industry – the tracking of genes that can increase milk production, and improve feed efficiency (how well a goat converts the feed it consumes into weight gain) and other disease resistance.

The initial research was in part funded by the Centre of Excellence for Goat Research and Innovation. The goat genotyping project now underway is supported in part through Growing Forward 2 (GF2), a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of GF2 programs in Ontario.

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