In all organisms, life-history traits are constrained by trade-offs, which may represent physiological limitations or be related to energy resource management. To detect trade-offs within a population, one promising approach is the use of artificial selection, because intensive selection on one trait can induce unplanned changes in others. In chickens, the breeding industry has achieved remarkable genetic progress in production and feed efficiency over the last 60 years. However, this may have been accomplished at the expense of other important biological functions, such as immunity. In the present study, we used three experimental lines of layer chicken—two that have been divergently selected for feed efficiency and one that has been selected for increased antibody response to inactivated Newcastle disease virus (ND3)—to explore the impact of improved feed efficiency on animals’ immunocompetence and, vice versa, the impact of improved antibody response on animals’ growth and feed efficiency. There were detectable differences between the low (R+) and high (R−) feed-efficiency lines with respect to vaccine-specific antibody responses and counts of monocytes, heterophils, and/or T cell population. The ND3 line presented reduced body weight and feed intake compared to the control line. ND3 chickens also demonstrated an improved antibody response against a set of commercial viral vaccines, but lower blood leucocyte counts. This study demonstrates the value of using experimental chicken lines that are divergently selected for RFI or for a high antibody production, to investigate the modulation of immune parameters in relation to growth and feed efficiency. Our results provide further evidence that long-term selection for the improvement of one trait may have consequences on other important biological functions. Hence, strategies to ensure optimal trade-offs among competing functions will ultimately be required in multi-trait selection programs in livestock.

中文翻译：

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评估蛋鸡实验品系的饲料效率、生长相关性状和免疫活性之间的权衡

在所有生物体中，生命史特征都受到权衡的限制，这可能代表生理限制或与能源管理有关。为了检测种群中的权衡，一种有前景的方法是使用人工选择，因为对一种性状的密集选择会导致其他性状的意外变化。在鸡方面，过去 60 年来，养殖业在生产和饲料效率方面取得了显着的遗传进步。然而，这可能是以牺牲其他重要的生物学功能为代价的，例如免疫。在目前的研究中，我们使用了三个蛋鸡实验品系——两个是根据饲料效率不同选择的，一个是为了增加对灭活新城疫病毒 (ND3) 的抗体反应而选择的——来探索提高饲料效率对动物免疫能力的影响和，反之亦然，改善抗体反应对动物生长和饲料效率的影响。在疫苗特异性抗体反应和单核细胞、嗜异性细胞和/或 T 细胞群的计数方面，低 (R+) 和高 (R-) 饲料效率品系之间存在可检测的差异。与对照品系相比，ND3品系表现出降低的体重和采食量。ND3 鸡还表现出针对一组商业病毒疫苗的改进抗体反应，但血液白细胞计数较低。本研究证明了使用针对 RFI 或高抗体生产不同选择的实验鸡系来研究与生长和饲料效率相关的免疫参数调节的价值。我们的结果提供了进一步的证据，表明长期选择改善一种性状可能会对其他重要的生物学功能产生影响。因此，在牲畜的多性状选择计划中，最终需要确保竞争功能之间最佳权衡的策略。我们的结果提供了进一步的证据，表明长期选择改善一种性状可能会对其他重要的生物学功能产生影响。因此，在牲畜的多性状选择计划中，最终需要确保竞争功能之间最佳权衡的策略。我们的结果提供了进一步的证据，表明长期选择改善一种性状可能会对其他重要的生物学功能产生影响。因此，在牲畜的多性状选择计划中，最终需要确保竞争功能之间最佳权衡的策略。