BACKGROUND Most fish breeding programs aim at improving growth rate and include feed conversion ratio (FCR) neither in the breeding goal nor in the selection index, although decreasing FCR is known to increase farm profit and decrease environmental impacts. This is because FCR is difficult to measure in fish that live in groups and FCR is assumed to have a favourable (negative) genetic correlation with growth, although the magnitude of this correlation is unknown. We investigated the effect of the genetic correlation between growth and FCR on the economic and environmental responses of a two-trait breeding goal (growth and FCR), compared to a single-trait breeding goal (growth only). Next, we evaluated the weights to assign to growth and FCR in a two-trait breeding goal to maximize sustainability of fish production. METHODS We used pseudo-best linear unbiased prediction (BLUP) index calculations to simulate a breeding program for sea bass. For the single-trait breeding goal, the trait in the breeding goal and in the index was thermal growth coefficient (TGC) and for the two-trait breeding goal, the traits in the breeding goal were TGC and FCR and the traits in the index were TGC and percentage of fat in the dorsal muscle (an indirect measure of FCR). We simulated responses to selection for genetic and phenotypic correlations between TGC and FCR ranging from 0 to - 0.8. Then, in the two-trait breeding goal, we calculated the economic return and the change in eutrophication when using economic values (EV) or environmental values (ENV). RESULTS When the genetic correlation between TGC and FCR was lower than - 0.45, we found major differences in economic returns and in eutrophication between single and two-trait breeding programs. At a correlation of - 0.25, the two-trait breeding goal based on EV increased economic return by 25% compared to the single-trait breeding goal, while using ENV decreased eutrophication by 1.34% per ton of fish produced after one generation of selection. CONCLUSIONS The genetic correlation between TGC and FCR affects the magnitude of economic losses due to omitting FCR in the breeding program. In addition, the genetic correlation affects the importance of choosing EV or ENV to reduce eutrophication and increase profit.

中文翻译：

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饲料转化率与生长率之间的遗传相关性会影响育种程序的设计，以实现更可持续的鱼类生产。

背景技术尽管已知降低鱼的FCR可以增加养殖场的利润并减少对环境的影响，但是大多数鱼的育种计划都旨在提高生长速度，并且既未将其饲料转化率（FCR）纳入育种目标，也未将其包括在选择指数中。这是因为在成群生活的鱼类中很难测量FCR，并且假定FCR与生长具有良好的（负）遗传相关性，尽管这种相关性的大小未知。我们研究了与单性状育种目标（仅生长）相比，生长和FCR之间的遗传相关性对两性育种目标（生长和FCR）的经济和环境响应的影响。接下来，我们评估了两个特征育种目标中分配给生长和FCR的权重，以最大程度地提高鱼类生产的可持续性。方法我们使用伪最佳线性无偏预测（BLUP）指数计算来模拟鲈鱼繁殖程序。对于单性状育种目标，育种目标和指标中的性状为热生长系数（TGC）；对于两个性状育种目标，育种目标中的性状为TGC和FCR，在指数中性状TGC和背肌脂肪百分比（FCR的间接指标）。我们模拟了TGC和FCR之间的遗传和表型相关选择响应，范围从0到-0.8。然后，在两性育种目标中，我们使用经济价值（EV）或环境价值（ENV）来计算经济收益和富营养化的变化。结果当TGC和FCR之间的遗传相关性低于-0.45时，我们发现单性育种和两性育种计划在经济收益和富营养化方面存在重大差异。当相关系数为-0.25时，基于EV的两性育种目标与单性状育种目标相比，可增加25％的经济回报，而使用ENV可使每一代选择后生产的每吨鱼的富营养化降低1.34％。结论由于在育种程序中省略了FCR，TGC和FCR之间的遗传相关性影响了经济损失的程度。此外，遗传相关性影响选择EV或ENV的重要性，以减少富营养化并增加利润。而使用ENV可使一代人选择后每吨鱼的富营养化降低1.34％。结论由于在育种程序中省略了FCR，TGC和FCR之间的遗传相关性影响了经济损失的程度。此外，遗传相关性影响选择EV或ENV的重要性，以减少富营养化并增加利润。而使用ENV可使一代人选择后每吨鱼的富营养化降低1.34％。结论由于在育种程序中省略了FCR，TGC和FCR之间的遗传相关性影响了经济损失的程度。此外，遗传相关性影响选择EV或ENV的重要性，以减少富营养化并增加利润。