Animal Breeding and Genomics, Wageningen University & Research, PO box 338, 6700 AH Wageningen, The Netherlands.
Poult Sci. 2019 Sep 1;98(9):3431-3442. doi: 10.3382/ps/pez250.
Mortality due to feather pecking (FP) has large economic and welfare consequences in the commercial poultry industry, and reduces survival of birds. With FP, the survival time of a hen depends both on her own genetic ability to avoid becoming the victim of FP (direct genetic effect; DGE), and on the genetic tendency of her group mates to perform FP (indirect genetic effect; IGE). Thus, to improve survival time of laying hens, it is important to use a breeding strategy that captures both the DGE and the IGE of selection candidates. Here, we investigate the prospects for solving mortality due to FP in laying hens by genetic selection. First, we review genetic parameters for survival time. Second, we use deterministic simulation to predict response to selection for 2 multi-trait crossbred breeding programs, a traditional recurrent testing scheme (RT) and a genomic selection scheme (GS). Finally, we investigate the prospects for sustained improvement of survival time when mortality becomes low. Results show that survival time has considerable heritable variation; most estimates of the total additive genetic standard deviation are larger than 1 mo. As expected, predicted single generation response to selection in survival time with GS is substantial larger than with RT. Particularly when the correlation between survival time and other breeding goal traits is zero, the GS scheme yields substantial improvement in survival time. For example, when mortality is 35%, the genetic correlation between survival time and other traits is 0, allowing for a 10% reduction of response in other traits, and when selection takes place in both the sire line and dam line, survival time can be improved with ∼23 D in one generation, using GS. Results, however, also show a strong decrease in heritability when mortality decreases, indicating that continued improvement becomes increasingly difficult. In summary, our results show that breeders can considerably reduce mortality due to FP with limited reduction of improvement in other breeding goal traits.
啄羽导致的死亡率（FP）对商业家禽业有重大的经济和福利影响，并降低了禽类的存活率。在 FP 情况下，母鸡的存活时间既取决于她自身避免成为 FP 受害者的遗传能力（直接遗传效应；DGE），也取决于她群体同伴进行 FP 的遗传倾向（间接遗传效应；IGE）。因此，为了提高蛋鸡的存活时间，使用既能捕捉到选择候选者的 DGE 又能捕捉到 IGE 的育种策略非常重要。在这里，我们研究了通过遗传选择解决蛋鸡 FP 死亡率的前景。首先，我们回顾了与存活时间有关的遗传参数。其次，我们使用确定性模拟预测了 2 个多性状杂交繁育计划的选择响应，一个是传统的反复测试方案（RT），另一个是基因组选择方案（GS）。最后，我们研究了当死亡率变低时持续提高存活时间的前景。结果表明，存活时间具有相当大的遗传变异性；大多数总加性遗传标准差的估计值都大于 1 个月。正如预期的那样，GS 方案在生存时间上的单代选择响应预测明显大于 RT。特别是当生存时间与其他育种目标性状之间的相关性为零时，GS 方案在生存时间上产生了实质性的改进。例如，当死亡率为 35%时，生存时间与其他性状之间的遗传相关性为 0，允许在其他性状上减少 10%的响应，并且当在父线和母线中都进行选择时，使用 GS 可以在一代中提高约 23 天的生存时间。然而，结果还表明，当死亡率降低时，遗传率会大幅下降，这表明持续改进变得越来越困难。总之，我们的研究结果表明，饲养员可以在不降低其他育种目标性状改进的情况下，显著降低 FP 导致的死亡率。
