Nutrigenomics and Fish Growth Endocrinology, Institute of Aquaculture Torre de la Sal (IATS-CSIC), 12595, Ribera de Cabanes, Castellón, Spain.
Fish Physiol Biochem. 2021 Feb;47(1):121-133. doi: 10.1007/s10695-020-00899-1. Epub 2020 Nov 13.
The present study evaluated, in an 18-month gilthead sea bream trial, the time course effects of genetics on individual size variation and growth compensation processes in families selected by heritable growth in the PROGENSA breeding program. Families categorized as fast, intermediate, and slow growing had different growth trajectories with a more continuous growth in fast growth families. This feature was coincident with a reduced size variation at the beginning of the trial that clustered together the half-sib families sharing the same father. Regression analysis evidenced that the magnitude of compensatory growth was proportional to the initial size variation with no rescaling of families at this stage. By contrast, the finishing growth depensation process can mask, at least partially, the previous size convergence. This reflects the different contribution across the production cycle of genetics in growth. How early-life experiences affect growth compensation at juvenile stages was also evaluated in a separate cohort, and intriguingly, a first mild-hypoxia pulse at 60-81 days post-hatching (dph) increased survival rates by 10%, preventing growth impairment when fish were exposed to a second hypoxia episode (112-127 dph). The early hypoxia experience did not have a negative impact on growth compensatory processes at juvenile stages. By contrast, a diminished capacity for growth compensation was found with repeated or late hypoxia experiences. All this reinforces the use of size variation as a main criterion for improving intensive fish farming and selective breeding.
本研究在为期 18 个月的金头鲷试验中评估了遗传对 PROGENSA 选育计划中通过遗传生长选择的家系个体大小变异和生长补偿过程的时程效应。快速、中速和慢速生长的家系具有不同的生长轨迹，快速生长家系的生长更为连续。这一特征伴随着试验初期大小变异的减少，使具有相同父本的半同胞家系聚集在一起。回归分析表明，补偿生长的幅度与初始大小变异成正比，在这个阶段没有对家系进行重新调整。相比之下，生长结束时的补偿过程至少部分掩盖了之前的大小趋同。这反映了遗传在生长过程中的不同贡献。早期生活经历如何影响幼鱼阶段的生长补偿也在另一个队列中进行了评估，有趣的是，孵化后 60-81 天（dph）的第一次轻度低氧脉冲将存活率提高了 10%，当鱼再次暴露于低氧环境（112-127 dph）时，防止了生长受损。早期低氧经历对幼鱼阶段的生长补偿过程没有负面影响。相比之下，重复或晚期低氧经历会导致生长补偿能力下降。所有这些都强化了将大小变异作为提高集约化养殖和选择性育种的主要标准的使用。
