Disease Resilience – Focused on Improving Pig Health

Chad Bierman, PhD, Geneticist, Genesus Inc.

What is disease resilience and why is it important?

Disease challenges in swine put downward pressure on the economics of pork production. Disease resilience is important because it is a phenotypic descriptor for individual animals or a population of animals, and it plays an important role in defining profitability in pork production. Resilience is defined as an animal’s ability to maintain performance under increased exposure to a pathogen. It is a combination of resistance and tolerance concepts. When identifying levels of health, resistance describes an animal’s ability to resist infection, thus limiting the pathogens’ ability to replicate additional pathogen. Tolerance describes an animal’s ability to tolerate infection by continuing to perform under increasing levels of the replicated pathogen inside the body. Resilient animals continue to perform under increasing levels of exposure to pathogens. By selecting for higher disease resilience, we can increase the level of resistance and tolerance in a population without needing to measure the amount of pathogen load present.

What role does genetics play in disease resilience?

Host genetics do play a role in disease resilience. Let’s say we want to measure growth, or score animals for visible health in a pen of health-challenged animals. There is going to be variation in those measurements. When we analyze that phenotypic variation and break it down into components caused by the environment or the animal itself, we can see there is a genetic component to these measures. Furthermore, we have identified specific regions of the genome where, depending on which forms of a gene have been inherited, will cause an animal to be more or less healthy. By measuring phenotypes at the quantitative level, and at the genomic level, we can say, without doubt, host genetics play a role in disease resilience.

Why is Genesus interested in disease resilience?

The Genesus mission is to develop and provide the best quality swine genetics to our customers. As our customers are driven by profitability, we strive to provide the best opportunity for that in the products we sell. Pigs that fail to thrive and survive are not profitable pigs.

What approaches will Genesus take to improve disease resilience?

A few approaches do exist for inserting disease resilience into the breeding goal of an animal breeding program. We continue to utilize traditional quantitative breeding strategies, with a twist to include genomics in the evaluation. Therefore, we effectively carry out a genomic selection program for disease resilience, which supports the other traits of economic relevance within the breeding program. In addition, the last decade of global disease research has identified specific gene markers within the porcine genome related to susceptibility of different diseases. Genesus is currently utilizing two of these markers in a marker-assisted selection approach, supplementing the breeding decisions that are made today. These decisions will impact resilience to PRRS and resistance to E.Coli in a beneficial manner.

What is the expected impact of improving a pig’s genetic merit for disease resilience?

This is an answer framed around sustainability, surrounded by the societal and economic impacts that a population of pigs requiring fewer inputs (fewer treatments, less antibiotic use) and providing larger outputs (increased gain, lower mortality, lower morbidity) would bring to the industry. The impact is potentially enormous. The timeline for impacting the pork industry is driven by the rate of genetic improvement in the trait, and the rate of adoption of a more disease resilient animal into the production system.

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