Berghof Tom V L, Bovenhuis Henk, Mulder Han A
Wageningen University & Research Animal Breeding and Genomics, Wageningen, Netherlands.
Front Genet. 2019 Dec 13;10:1216. doi: 10.3389/fgene.2019.01216. eCollection 2019.
Resilience is the capacity of an animal to be minimally affected by disturbances or to rapidly return to the state pertained before exposure to a disturbance. Less resilient animals are expected to be more susceptible to environmental perturbations, such as diseases, and will consequently show more and/or greater fluctuations in production than more resilient animals. Natural antibodies (NAb) are antibodies recognizing antigens without previous exposure to these, and are hypothesized to be an indication of general disease resistance. The objective of this research was to investigate genetic parameters of resilience indicators based on standardized body weight (BW) deviations and to investigate its relation with immunity (i.e. NAb) and disease resistance. Keyhole limpet hemocyanin-binding NAb were measured in layer chickens, which were selectively bred for high and low keyhole limpet hemocyanin-binding NAb levels during six generations. In addition, BW data of these layers were collected on a four-weekly interval from 4 weeks of age until 32 weeks of age. Standardized deviations of BW from an individual were compared to lines' average BW (i.e. across individuals), and these were used to calculate resilience indicators: natural logarithm-transformed variance [ln(variance)], skewness, and lag-one autocorrelation of deviations (i.e. all within an individual). Heritabilities of resilience indicators were between 0.09 and 0.11. Genetic correlations between the three resilience indicators were between -0.20 and 0.40 (with high SE), which might suggest that the resilience indicators capture different aspects of resilience. Genetic correlations between resilience indicators and NAb were close to zero, which suggests that the resilience indicators and NAb capture different aspects of immunity. This might indicate that, in this dataset, environmental perturbations are only to a small extent affected by disease incidence, possibly due to a lack of disease occurrence. However, a lower estimated breeding value for ln(variance) was predictive for lower lesion scores after an avian pathogenic inoculation and vice versa. In conclusion, this study shows that there is genetic variation in resilience indicators based on BW deviations in layer chickens, which opens up possibilities to improve resilience by means of selective breeding.
恢复力是指动物受干扰影响最小或在暴露于干扰后迅速恢复到之前状态的能力。预计恢复力较低的动物对环境扰动（如疾病）更敏感，因此与恢复力较强的动物相比，其生产性能会出现更多和/或更大的波动。天然抗体（NAb）是在未预先接触抗原的情况下就能识别抗原的抗体，据推测它是一般抗病能力的一个指标。本研究的目的是基于标准化体重（BW）偏差研究恢复力指标的遗传参数，并研究其与免疫力（即NAb）和抗病能力的关系。在蛋鸡中测量了匙孔血蓝蛋白结合型NAb，这些蛋鸡在六个世代中被选择性培育成匙孔血蓝蛋白结合型NAb水平高和低的品系。此外，从4周龄到32周龄，每隔四周收集这些蛋鸡的体重数据。将个体体重的标准化偏差与品系的平均体重（即 across individuals）进行比较，并用于计算恢复力指标：自然对数转换方差[ln（方差）]、偏度和偏差的滞后一阶自相关（即均在个体内部）。恢复力指标的遗传力在0.09至0.11之间。三个恢复力指标之间的遗传相关性在-0.20至0.40之间（标准误较高），这可能表明恢复力指标反映了恢复力的不同方面。恢复力指标与NAb之间的遗传相关性接近零，这表明恢复力指标和NAb反映了免疫力的不同方面。这可能表明，在该数据集中，环境扰动仅在很小程度上受疾病发生率影响，可能是由于疾病发生率较低。然而，ln（方差）的较低估计育种值预示着禽致病性接种后病变评分较低，反之亦然。总之，本研究表明，基于蛋鸡体重偏差的恢复力指标存在遗传变异，这为通过选择性育种提高恢复力开辟了可能性。
