Resistencia y resiliencia a las enfermedades en las razas de rumiantes locales: un enfoque en América del Sur

Interest genetic variability loss has taken importance not only the production but also because it may have negative effect on the epidemiology of animal diseases. Livestock activity can present considerable periodic economic losses due to animal disposal, reduced productivity, failure to express the genetic potential of animals, treatment costs, labour and professional assistance, closing of trade due to sanitary barriers and competition with foreign markets. Thus, disease resistance is a desired attribute in livestock production and animal health may be limiting in cattle production systems. Some confusion in terminology exist: resistance is defined as the ability of the host to exert some degree of control over the pathogen’s life cycle, while tolerance defines the impact of infection on animal performance. A concept very close to tolerance is resilience, which can be defined as maintaining the animal’s productive capacity in the face of infection. There are numerous reports indicating local breeds as an important reservoir of naturally genetics resistance to disease as a process of adaptability to the environment. Referring to the main diseases of domestic animals (tuberculosis, brucellosis, foot-and-mouth disease, etc.), numerous genes have been identified and studied as biomarkers for resistance and tolerance like the BOLA complex, CD, NOD and SLC11A1 genes among the most important. Although the limiting factor for breeding programs to include genetic disease resistance is the need to quantify resistance phenotypes. This can be expensive and logistically difficult, and is a significant barrier to selection for disease resistance. For this reason, disease resistance characteristics are an attractive target for genomic studies and are generally the subject of these studies.