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.