Johnes resiliance critical in deer herds

Peel Forest Estate, a South Canterbury deer stud, is marketing stags from a programme designed to select for resilience to Johnes disease, a wasting illness closely related to tuberculosis reports The ODT. This is thought to be a world-first for any species or breed of livestock. University of Otago immunologist Prof Frank Griffin said the term resilient was chosen carefully. Unlike resistance, which was the ability to remain free from infection, resilience was the ability to stay healthy and productive following exposure to a specific infectious pathogen. Johnes is widespread in dairy herds and sheep flocks around the world and is a problem in many NZ deer herds, where it can cause major losses in young stock. There is no effective treatment. After Peel Forest diagnosed Johnes disease in 2000, owner Graham Carr approached Prof Griffin. He had a number of valuable bloodlines that would be lost to the industry unless he could assure potential buyers that they were free from the disease. He said Peel Forests' comprehensive pedigree database helped his group identify susceptible and resilient bloodlines, assisted by postmortem data from culled animals. The stud had been involved in embryo transfer programmes and had eight extremely pure bloodlines, providing an opportunity for genetic study that Prof Griffin believed was unprecedented for domestic livestock. It had produced some of the most useful information Prof Griffin had seen in 40 years of research. The study found resilience to the disease had a genetic basis and was linked to certain bloodlines. For example, a bloodline called B11 was extremely resilient and by chance was also associated with high breeding values for weight gain.