Zak Louisa J, Gaustad Ann Helen, Bolarin Alfonso, Broekhuijse Marleen L W J, Walling Grant A, Knol Egbert F
Topigs Norsvin Research Center, Beuningen, The Netherlands.
Norsvin, Hamar, Norway.
Mol Reprod Dev. 2017 Sep;84(9):1004-1011. doi: 10.1002/mrd.22875. Epub 2017 Sep 11.
Reproductive traits are complex, and desirable reproductive phenotypes, such as litter size or semen quality, are true polygenetic traits determined by multiple gene regulatory pathways. Each individual gene contributes to the overall variation in these traits, so genetic improvements can be achieved using conventional selection methodology. In the past, a pedigree-based-relationship matrix was used; this is now replaced by a combination of pedigree-based- and genomic-relationship matrices. The heritability of reproductive traits is low to moderate, so large-scale data recording is required to identify specific, selectable attributes. Male reproductive traits-including ejaculate volume and sperm progressive motility-are moderately heritable, and could be used in selection programs. A few high-merit artificial-insemination boars can impact many sow populations, so additional knowledge about male reproduction-specifically pre-pubertal detection of infertility and the technologies of semen cryopreservation and sex sorting-should further improve global breeding efforts. Conversely, female pig reproduction is currently a limiting factor of genetic improvement. Litter size and farrowing interval are the main obstacles to increasing selection intensity and to reducing generation interval in a breeding program. Age at puberty and weaning-to-estrus interval can be selected for, thereby reducing the number of non-productive days. The number of piglets born alive and litter weights are also reliably influenced by genetic selection. Characterization of genotype-environment interactions will provide opportunities to match genetics to specific farm systems. Continued investment to understand physiological models for improved phenotyping and the development of technologies to facilitate pig embryo production for genetic selection are warranted to ensure optimal breeding in future generations.
繁殖性状很复杂，理想的繁殖表型，如产仔数或精液质量，是由多个基因调控途径决定的真正的多基因性状。每个个体基因都对这些性状的总体变异有贡献，因此可以使用传统的选择方法实现遗传改良。过去使用基于系谱的亲缘关系矩阵；现在已被基于系谱和基因组的亲缘关系矩阵相结合所取代。繁殖性状的遗传力低至中等，因此需要大规模数据记录来识别特定的、可选择的属性。雄性繁殖性状，包括射精量和精子前向运动能力，具有中等遗传力，可用于选择计划。少数高优人工授精公猪可影响许多母猪群体，因此关于雄性繁殖的更多知识，特别是青春期前不育的检测以及精液冷冻保存和性别分选技术，应进一步改善全球育种工作。相反，雌性猪的繁殖目前是遗传改良的限制因素。产仔数和产仔间隔是育种计划中增加选择强度和缩短世代间隔的主要障碍。可以选择初情期年龄和断奶至发情间隔，从而减少非生产天数。产活仔数和窝重也受到遗传选择的可靠影响。基因型 - 环境相互作用的表征将为使遗传与特定农场系统相匹配提供机会。持续投入以了解用于改进表型分析的生理模型以及开发促进猪胚胎生产用于遗传选择的技术，对于确保后代的最佳育种是必要的。
