ReproGen Animal BioScience Group, Faculty of Veterinary Science, University of Sydney Sydney, NSW, Australia.
Front Genet. 2012 Dec 14;3:281. doi: 10.3389/fgene.2012.00281. eCollection 2012.
The benefits of improved health and welfare in pigs have driven refinements in management and selection practices, one of which is the production of pig phenotypes that can maintain health and productivity by improving response against pathogens. Selection has traditionally been made for host resistance; but the alternative host defence mechanism-host tolerance-is now being considered, as breeding for disease tolerance allows maintenance of high performance across environments of increasing pathogenic load. A distinction must be made between these two mechanisms as they vary in their influence on host-pathogen interactions and pathogen evolution, and consequently on the results of breeding programs. Many pig production studies have failed to distinguish between resistance and tolerance; although a distinction may not always be possible. This article reviews current perspectives in selective breeding for disease resistance and tolerance in growing pigs, and the attendant industry implications. To assess the viability of breeding for resistance and/or tolerance for improved response to disease and other environmental challenges, we propose the use of routine farm records, instead of data measurements taken from laboratory experiments. Consequently, a number of factors need to be taken into account simultaneously for a multidimensional modeling approach. This includes not only genotype and disease variables, but also descriptors of the environment, as well as any possible interactions. It may not be feasible to record individual pathogen loads, and therefore true tolerance, on farm using routinely collected data. However, it may be estimated with group (farm) means, or other proxy measures. Although this results in a bias, this may still be useful for modeling and quantifying resistance and tolerance. We can then quantify success of selection, and this may enable us to decide whether to select for disease resistance versus disease tolerance.
改善猪的健康和福利的好处推动了管理和选择实践的改进，其中之一是生产能够通过改善对病原体的反应来维持健康和生产力的猪表型。传统上，选择是针对宿主抗性进行的；但是现在正在考虑替代的宿主防御机制——宿主耐受性，因为对疾病耐受性的选育允许在病原体负荷不断增加的环境中保持高性能。这两种机制必须加以区分，因为它们在宿主-病原体相互作用和病原体进化以及对选育计划结果的影响方面存在差异。许多猪生产研究未能区分抗性和耐受性；尽管有时可能无法区分。本文综述了当前在生长猪疾病抗性和耐受性选育方面的观点，以及随之而来的行业影响。为了评估为改善对疾病和其他环境挑战的反应而选育抗性和/或耐受性的可行性，我们建议使用常规农场记录，而不是来自实验室实验的数据测量。因此，需要同时考虑许多因素来进行多维建模方法。这不仅包括基因型和疾病变量，还包括环境描述符以及任何可能的相互作用。使用常规收集的数据在农场记录个体病原体负荷可能是不可行的，因此真正的耐受性可能无法实现。然而，可以使用群体（农场）平均值或其他代理措施进行估计。虽然这会导致偏差，但对于建模和量化抗性和耐受性仍然可能有用。我们可以量化选择的成功，这可能使我们能够决定是选择疾病抗性还是疾病耐受性。
