Disease resistant sheep the focus of PhD thesis

The ability to breed sheep resistant to paratuberculosis, a chronic disease which leads to production loss, is the goal of PhD student Rao Dukkipati. The disease, while not fatal, makes sheep lose weight and produce less wool.

Studies estimate around 70 per cent of New Zealand’s 40 million sheep are infected with the disease, costing the industry about $10 million a year.

Dr Dukkipati, who graduated yesterday, identified genetic markers for immune responses to paratuberculosis vaccination in 900 merino sheep in Australia.

Six genotypes and four alleles at six marker loci were found to be either “probably” or “most likely” to be associated with immune responses to vaccination, he says.

“The presence of a particular marker genotype or allele may lead to a lower or higher response to the vaccine. It is likely that they will behave similarly to the natural disease.”

Identifying the markers could lead to the selective breeding of disease resistant animals.

“These animals would be bred exclusively to improve genetic resistance to paratuberculosis.”

Dr Dukkipati came to Massey from India in 2002 and completed his PhD at the Insitute of Veterinary, Animal and Biological Sciences last year. His wife, Kavitha Kongara, is also working on her doctoral thesis in clinical veterinary science at Massey.

The couple have become New Zealand citizens and Dr Dukkapati is now employed at the institute as a researcher.

“We were hoping to graduate at the same time, however she will defend her thesis later this month and graduate at the next ceremony,” he says.

“I’m working now on a sub-vaccine which will work against paratuberculosis. At the moment there are a number of commercial vaccines, but none protect the animals completely.”