Resilience is the capacity of an animal to be minimally affected by disturbances or to rapidly return to its initial state before exposure to a disturbance. Resilient livestock are desired because of their improved health and increased economic profit. Genetic improvement of resilience may also lead to trade-offs with production traits. Recently, resilience indicators based on longitudinal data have been suggested, but they need further evaluation to determine whether they are indeed predictive of improved resilience, such as disease resilience. This study investigated different resilience indicators based on deviations between expected and observed egg production (EP) by exploring their genetic parameters, their possible trade-offs with production traits, and their relationships with antibody traits in chickens. Egg production in a nucleus breeding herd environment based on 1-week-, 2-week-, or 3-week-intervals of two purebred chicken lines, a white egg-laying (33,825 chickens) and a brown egg-laying line (34,397 chickens), were used to determine deviations between observed EP and expected average batch EP, and between observed EP and expected individual EP. These deviations were used to calculate three types of resilience indicators for two life periods of each individual: natural logarithm-transformed variance (ln(variance)), skewness, and lag-one autocorrelation (autocorrelation) of deviations from 25 to 83 weeks of age and from 83 weeks of age to end of life. Then, we estimated their genetic correlations with EP traits and with two antibody traits. The most promising resilience indicators were those based on 1-week-intervals, as they had the highest heritability estimates (0.02–0.12) and high genetic correlations (above 0.60) with the same resilience indicators based on longer intervals. The three types of resilience indicators differed genetically from each other, which indicates that they possibly capture different aspects of resilience. Genetic correlations of the resilience indicator traits based on 1-week-intervals with EP traits were favorable or zero, which means that trade-off effects were marginal. The resilience indicator traits based on 1-week-intervals also showed no genetic correlations with the antibody traits, which suggests that they are not informative for improved immunity or vice versa in the nucleus environment. This paper gives direction towards the evaluation and implementation of resilience indicators, i.e. to further investigate resilience indicator traits based on 1-week-intervals, in breeding programs for selecting genetically more resilient layer chickens.

中文翻译：

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鸡的恢复力遗传学及其与产蛋性状和抗体性状的关系


复原力是指动物受干扰影响最小或在受到干扰之前迅速恢复到初始状态的能力。具有韧性的牲畜因其健康状况改善和经济利润增加而受到人们的欢迎。复原力的遗传改良也可能导致与生产性状的权衡。最近，有人提出了基于纵向数据的复原力指标，但需要进一步评估，以确定它们是否确实可以预测复原力的提高，例如疾病复原力。本研究根据预期产蛋量 (EP) 和观察到产蛋量 (EP) 之间的偏差，通过探索其遗传参数、与生产性状的可能权衡以及与鸡抗体性状的关系，研究了不同的弹性指标。核心种鸡群环境中的产蛋量基于两个纯种鸡系、一个白蛋产鸡系（33,825 只鸡）和一个棕色蛋产鸡系（34,397 只）的 1 周、2 周或 3 周间隔鸡），用于确定观察到的 EP 与预期平均批次 EP 之间的偏差，以及观察到的 EP 与预期个体 EP 之间的偏差。这些偏差用于计算每个个体两个生命周期的三类弹性指标：25至83周龄偏差的自然对数转换方差（ln(variance)）、偏度和滞后一自相关（autocorrelation）从 83 周龄到生命终结。然后，我们估计了它们与 EP 性状和两种抗体性状的遗传相关性。最有希望的恢复力指标是基于 1 周间隔的指标，因为它们具有最高的遗传力估计值（0.02-0.12）和高遗传相关性（高于 0.60）具有基于更长间隔的相同弹性指标。这三种类型的复原力指标在本质上彼此不同，这表明它们可能捕捉到复原力的不同方面。基于 1 周间隔的复原力指标性状与 EP 性状的遗传相关性良好或为零，这意味着权衡效应很小。基于 1 周间隔的弹性指标特征也显示出与抗体特征没有遗传相关性，这表明它们对于提高免疫力没有提供信息，反之亦然。本文为复原力指标的评估和实施提供了方向，即在选择遗传上更具复原力的蛋鸡的育种计划中，进一步研究基于1周间隔的复原力指标性状。