This important identification of – in this study, genetic markers for PRRS tolerance – is a significant advance in the swine industry. But how does it impact producers?

According to many industry estimates, the mortality, abortions and impaired growth performance associated with Porcine Reproductive and Respiratory Syndrome (PRRS) is estimated to result in $560 million of lost annual income for US producers alone. A perennially difficult disease to eradicate, PRRS challenges producer profitability through higher medical costs, loss of production efficiency, failure of animals to thrive, death loss and additional labor, to name just a few of the production impacts.

“There have been reports of genetic differences among pigs in their tolerance to pathogen infections,“ says Archie Clutter, Ph.D., Vice President of Research and Development for Newsham Choice Genetics. “This suggests that within-line selection for disease tolerance could be an effective way to improve the health of commercial pigs, but conventional methods of testing and selection would require that genetic nucleus animals or their relatives be challenged with a disease environment.

“Newsham Choice Genetics has a long history of applying genomic discoveries in selection as a way to accelerate the rate of genetic progress that is possible with traditional selection methods,“ he adds, “and disease tolerance is an excellent example of a trait for which genomics may provide great value over any potential alternatives. Genotyping for genomic markers discovered to have associations with disease response could be used to select genetic nucleus animals with favorable breeding value for disease tolerance, while maintaining the high-health status of the genetic nucleus herd.“

For these reasons, an ambitious project was initiated in 2006 in which Newsham Choice Genetics has worked to discover and map genes associated with health traits in pigs.

The study included more than 1,100 fully pedigreed pigs from Newsham’s EBX and GX lines, each challenged during the nursery period with specific amounts of a well-characterized field strain of the PRRS virus.

Designed to not only reveal new information about variation in the basic underlying response to the PRRS challenge, the study also aimed to characterize each piglet’s overall health and performance in response to the challenge.

“Each of the pigs was genotyped for more than 64,000 markers throughout the genome so that the locations of genes contributing to differences in disease tolerance and animal health could be determined,“ Clutter explains. “Consistent with what we’ve observed in our genomics discoveries related to production and reproduction traits, each of the disease tolerance traits we’ve studied is genetically complex and affected by many genes. While we expect some of these genes to be specific to a PRRS response, we expect many to be more generally important for disease tolerance and animal health.

“We are now completing validation of these initial discoveries in which we will use independent samples collected from disease breaks in the field to confirm the marker associations with pig health and any associations with performance traits.“

The magnitude of this study will result in unprecedented power to discover selection tools that can be applied directly in the lines of Newsham Choice Genetics to improve genetic merit for disease tolerance. Timeline for the project includes the first use of these selection tools for improved disease tolerance in the first half of 2011.

Further Reading

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Find out more information on PRRS by clicking here.