Department of Animal Sciences, Animal Breeding and Genetics Group, University of Göttingen, 37075 Göttingen, Germany.
Poult Sci. 2010 Apr;89(4):658-67. doi: 10.3382/ps.2009-00543.
Due to consistent increases of inbreeding of on average 0.95% per generation in layer populations, selection tools should consider both genetic gain and genetic relationships in the long term. The optimum genetic contribution theory using official estimated breeding values for egg production was applied for 3 different lines of a layer breeding program to find the optimal allocations of hens and sires. Constraints in different scenarios encompassed restrictions related to additive genetic relationships, the increase of inbreeding, the number of selected sires and hens, and the number of selected offspring per mating. All these constraints enabled higher genetic gain up to 10.9% at the same level of additive genetic relationships or in lower relationships at the same gain when compared with conventional selection schemes ignoring relationships. Increases of inbreeding and genetic gain were associated with the number of selected sires. For the lowest level of the allowed average relationship at 10%, the optimal number of sires was 70 and the estimated breeding value for egg production of the selected group was 127.9. At the highest relationship constraint (16%), the optimal number of sires decreased to 15, and the average genetic value increased to 139.7. Contributions from selected sires and hens were used to develop specific mating plans to minimize inbreeding in the following generation by applying a simulated annealing algorithm. The additional reduction of average additive genetic relationships for matings was up to 44.9%. An innovative deterministic approach to estimate kinship coefficients between and within defined selection groups based on gene flow theory was applied to compare increases of inbreeding from random matings with layer populations undergoing selection. Large differences in rates of inbreeding were found, and they underline the necessity to establish selection tools controlling long-term relationships. Furthermore, it was suggested to use optimum genetic contribution theory for conservation schemes or, for example, the experimental line in our study.
由于鸡群的平均近交系数每代增加 0.95%，选择工具应长期考虑遗传增益和遗传关系。本研究应用最优遗传贡献理论，利用蛋鸡生产的官方估计育种值，对一个蛋鸡育种项目的 3 个不同品系进行了研究，以确定母鸡和公鸡的最佳分配。不同场景下的约束条件包括与加性遗传关系、近交系数增加、选择的公鸡和母鸡数量、每轮交配选择的后代数量相关的限制。与忽略遗传关系的常规选择方案相比，所有这些约束条件都能在相同的加性遗传关系水平上或在较低的遗传关系水平上获得更高的遗传增益，最高可达 10.9%。近交系数和遗传增益的增加与选择的公鸡数量有关。在允许的平均关系最低水平 10%时，最优的公鸡数量为 70 只，选择组的蛋鸡生产估计育种值为 127.9。在最高的关系约束（16%）下，最优的公鸡数量减少到 15 只，平均遗传值增加到 139.7。利用选择的公鸡和母鸡的贡献，通过应用模拟退火算法，开发了特定的交配计划，以最大限度地减少下一代的近交。平均加性遗传关系的额外减少高达 44.9%。应用基于基因流理论的定义选择组内和组间亲缘系数的创新确定性方法，比较了选择鸡群与随机交配鸡群的近交系数增加情况。发现近交率的差异很大，这突显了建立控制长期关系的选择工具的必要性。此外，还建议使用最优遗传贡献理论来制定保护计划，或者在我们的研究中，例如，应用于实验线。
