Mulder H A, Rashidi H
J Anim Sci. 2017 Aug;95(8):3346-3358. doi: 10.2527/jas.2017.1479.
Response to infection in animals has 2 main mechanisms: resistance (ability to control pathogen burden) and tolerance (ability to maintain performance given the pathogen burden). Selection on disease resistance and tolerance to infections seems a promising avenue to increase productivity of animals in the presence of disease infections, but it is hampered by a lack of records of pathogen burden of infected animals. Selection on resilience (ability to maintain performance regardless of pathogen burden) may, therefore, be an alternative pragmatic approach, because it does not need records of pathogen burden. Therefore, the aim of this study was to assess response to selection in resistance and tolerance when selecting on resilience compared with direct selection on resistance and tolerance. Monte Carlo simulation was used combined with selection index theory to predict responses to selection. Using EBV for resilience in the absence of records for pathogen burden resulted in favorable responses in resistance and tolerance to infections, with higher responses in tolerance than in resistance. If resistance and tolerance were unfavorably correlated, lower selection responses were obtained, especially in resistance. When the genetic correlation was very unfavorable, the selection response in tolerance became negative. Results showed that lower selection responses in resistance and tolerance were obtained when the frequency of disease outbreaks was 10% rather than 50% of the contemporary groups. The efficiency of selection on EBV for resilience compared with selection on EBV for resistance and tolerance was, however, not affected by the frequency of disease outbreaks. When records on pathogen burden were available, selection responses in resistance, tolerance, and the total breeding goal were 3 to 28%, 66 to 398%, and 2 to 11% higher, respectively, than when using the EBV for resilience, showing a clear benefit of recording pathogen burden. This study shows that selection on resilience is a pragmatic way of increasing disease resistance and tolerance to infections in the absence of records on pathogen burden, but recording pathogen burden would yield higher selection responses in resistance and tolerance.
抗性（控制病原体负荷的能力）和耐受性（在存在病原体负荷的情况下维持性能的能力）。在存在疾病感染的情况下，选择抗病性和对感染的耐受性似乎是提高动物生产力的一条有前途的途径，但由于缺乏感染动物病原体负荷的记录而受到阻碍。因此，选择恢复力（无论病原体负荷如何都能维持性能的能力）可能是一种实用的替代方法，因为它不需要病原体负荷的记录。因此，本研究的目的是评估在选择恢复力时与直接选择抗性和耐受性相比，在抗性和耐受性方面的选择反应。结合选择指数理论使用蒙特卡罗模拟来预测选择反应。在没有病原体负荷记录的情况下使用 EBV 进行恢复力选择，对感染的抗性和耐受性产生了有利的反应，耐受性的反应高于抗性。如果抗性和耐受性呈负相关，则选择反应较低，尤其是在抗性方面。当遗传相关性非常不利时，耐受性的选择反应变为负数。结果表明，当疾病爆发频率为当代群体的 10%而不是 50%时，抗性和耐受性的选择反应较低。然而，与基于 EBV 选择抗性和耐受性相比，基于 EBV 选择恢复力的选择效率不受疾病爆发频率的影响。当有病原体负荷记录时，抗性、耐受性和总育种目标的选择反应分别比使用 EBV 进行恢复力选择时高 3%至 28%、66%至 398%和 2%至 11%，这表明记录病原体负荷有明显益处。本研究表明，在没有病原体负荷记录的情况下，选择恢复力是提高对感染的抗病性和耐受性的实用方法，但记录病原体负荷将在抗性和耐受性方面产生更高的选择反应。
