Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway.
Research Institute for Aquaculture No. 2 (RIA2), Ho Chi Minh City, Vietnam.
J Fish Dis. 2021 Feb;44(2):201-210. doi: 10.1111/jfd.13279. Epub 2020 Nov 20.
The aim of this study was to analyse four cohabitation challenge-test experiments with Mekong striped catfish (Pangasianodon hypophthalmus) against the bacterium Edwardsiella ictaluri. The data were genetically analysed per experiment by three models: 1) a cross-sectional linear model; 2) a cross-sectional threshold model; and 3) a linear survival model, at both 50% mortality (for models 1 and 2) and at the end of the test (for all three models). In two of the experiments (3 and 4) that were carried out in two replicated tanks, the predicted family effects (sum of sire, dam and common environmental effects) in each tank were correlated with the family survival in the other replicated tank (cross-validation). The heritability estimates of resistance to E. ictaluri infection were ≤ 0.012 with the survival model, and up to 0.135 - 0.220 (50% survival) and 0.085 and 0.174 (endpoint survival) for the cross-sectional linear and threshold models, respectively. The challenge test should aim for an endpoint survival that ceases naturally at 50%. Then, genetic analysis should be carried out for survival at the endpoint (reflecting susceptibility) with a simple cross-sectional linear model.
本研究旨在分析湄公河巨型鲶鱼（Pangasianodon hypophthalmus）对爱德华氏菌（Edwardsiella ictaluri）的 4 个同居挑战测试实验。每个实验的数据均通过 3 种模型进行遗传分析：1）横断面线性模型；2）横断面阈值模型；3）线性生存模型，死亡率均为 50%（模型 1 和模型 2）和试验结束时（所有 3 种模型）。在两个重复水槽中进行的两个实验（实验 3 和实验 4）中，每个水槽中的预测家系效应（父本、母本和共同环境效应之和）与另一个重复水槽中的家系生存情况相关（交叉验证）。采用生存模型估计对 E. ictaluri 感染的抗性遗传力估计值≤0.012，而横断面线性和阈值模型的估计值分别高达 0.135-0.220（50%存活率）和 0.085-0.174（终点存活率）。挑战测试应以自然停止在 50%的终点存活率为目标。然后，应使用简单的横断面线性模型对终点存活率（反映易感性）进行遗传分析。
