Animal Breeding and Genomics Centre, Wageningen University, PO Box 338, 6700 AH, Wageningen, The Netherlands.
Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350, Jouy-en-Josas, France.
Genet Sel Evol. 2020 Feb 7;52(1):5. doi: 10.1186/s12711-020-0524-0.
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.
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).
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.
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.
大多数鱼类养殖计划旨在提高生长速度，并且既不在养殖目标中也不在选择指数中包含饲料转化率（FCR），尽管降低 FCR 已知可以增加农场利润并减少环境影响。这是因为在生活在群体中的鱼类中，FCR 很难测量，并且 FCR 与生长具有有利（负）遗传相关性，尽管这种相关性的大小尚不清楚。我们研究了生长和 FCR 之间遗传相关性对两性状养殖目标（生长和 FCR）的经济和环境响应的影响，与单性状养殖目标（仅生长）相比。接下来，我们评估了在两性状养殖目标中分配给生长和 FCR 的权重，以最大限度地提高鱼类生产的可持续性。
我们使用伪最佳线性无偏预测（BLUP）指数计算来模拟鲈鱼的养殖计划。对于单性状养殖目标，养殖目标和指数中的性状是热生长系数（TGC），对于两性状养殖目标，养殖目标中的性状是 TGC 和饲料转化率（FCR），指数中的性状是 TGC 和背部肌肉中的脂肪百分比（FCR 的间接衡量指标）。我们模拟了遗传和表型相关性之间的选择响应，范围从 0 到-0.8。然后，在两性状养殖目标中，我们计算了使用经济价值（EV）或环境价值（ENV）时的经济回报和富营养化变化。
当 TGC 和 FCR 之间的遗传相关性低于-0.45 时，我们发现单性状和两性状养殖计划之间在经济回报和富营养化方面存在重大差异。在相关性为-0.25 时，基于 EV 的两性状养殖目标与单性状养殖目标相比，经济回报增加了 25%，而使用 ENV 可使每一代选择后每生产一吨鱼减少 1.34%的富营养化。
TGC 和 FCR 之间的遗传相关性会影响在养殖计划中忽略 FCR 所导致的经济损失的大小。此外，遗传相关性会影响选择 EV 或 ENV 以减少富营养化和增加利润的重要性。
