Alemu Setegn W, Calus Mario P L, Muir William M, Peeters Katrijn, Vereijken Addie, Bijma Piter
Department of Molecular Biology and Genetics, Center for Quantitative Genetics and Genomics, Aarhus University, 8830, Tjele, Denmark.
Animal Breeding and Genomics Centre, Wageningen University and Research, 6700 AH, Wageningen, The Netherlands.
Genet Sel Evol. 2016 Sep 13;48(1):68. doi: 10.1186/s12711-016-0247-4.
Mortality due to cannibalism causes both economic and welfare problems in laying hens. To limit mortality due to cannibalism, laying hens are often beak-trimmed, which is undesirable for animal welfare reasons. Genetic selection is an alternative strategy to increase survival and is more efficient by taking heritable variation that originates from social interactions into account, which are modelled as the so-called indirect genetic effects (IGE). Despite the considerable heritable variation in survival time due to IGE, genetic improvement of survival time in laying hens is still challenging because the detected heritable variation of the trait with IGE is still limited, ranging from 0.06 to 0.26, and individuals that are still alive at the end of the recording period are censored. Furthermore, survival time records are available late in life and only on females. To cope with these challenges, we tested the hypothesis that genomic prediction increases the accuracy of estimated breeding values (EBV) compared to parental average EBV, and increases response to selection for survival time compared to a traditional breeding scheme. We tested this hypothesis in two lines of brown layers with intact beaks, which show cannibalism, and also the hypothesis that the rate of inbreeding per year is lower for genomic selection than for the traditional breeding scheme.
The standard deviation of genomic prediction EBV for survival time was around 22 days for both lines, indicating good prospects for selection against mortality in laying hens with intact beaks. Genomic prediction increased the accuracy of the EBV by 35 and 32 % compared to the parent average EBV for the two lines. At the current reference population size, predicted response to selection was 91 % higher when using genomic selection than with the traditional breeding scheme, as a result of a shorter generation interval in males and greater accuracy of selection in females. The predicted rate of inbreeding per generation with truncation selection was substantially lower for genomic selection than for the traditional breeding scheme for both lines.
Genomic selection for socially affected traits is a promising tool for the improvement of survival time in laying hens with intact beaks.
同类相食导致的死亡率给蛋鸡养殖带来了经济和福利问题。为了限制同类相食造成的死亡率，蛋鸡常进行断喙处理，但出于动物福利原因，这是不可取的。基因选择是提高存活率的一种替代策略，通过考虑源自社会互动的遗传变异（即所谓的间接遗传效应，IGE），这种策略更为有效。尽管由于IGE导致存活时间存在相当大的遗传变异，但蛋鸡存活时间的遗传改良仍具有挑战性，因为检测到的具有IGE性状的遗传变异仍然有限，范围在0.06至0.26之间，并且在记录期结束时仍存活的个体被截尾。此外，存活时间记录在生命后期才可得，且仅针对雌性。为应对这些挑战，我们检验了以下假设：与亲本平均估计育种值（EBV）相比，基因组预测提高了估计育种值的准确性，并且与传统育种方案相比，提高了对存活时间选择的响应。我们在两系完整喙的褐壳蛋鸡中检验了这一假设，这两系蛋鸡表现出同类相食现象，同时还检验了基因组选择每年的近亲繁殖率低于传统育种方案这一假设。
两系蛋鸡存活时间的基因组预测EBV标准差均约为22天，这表明对于完整喙蛋鸡的死亡率选择具有良好前景。与两系的亲本平均EBV相比，基因组预测使EBV的准确性提高了35%和32%。在当前参考群体规模下，由于雄性世代间隔较短且雌性选择准确性更高，使用基因组选择时预测的选择响应比传统育种方案高91%。对于两系，基因组选择的截断选择每代预测的近亲繁殖率均显著低于传统育种方案。
对受社会影响性状的基因组选择是提高完整喙蛋鸡存活时间的一种有前景的工具。
