Basrur P K, King W A
Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada.
Rev Sci Tech. 2005 Apr;24(1):31-49.
In the past, domesticated animals were genetically improved by identifying meritorious individuals, mating animals displaying desired traits, continued breeding of related animals to perpetuate their superior traits and crossbreeding when inbreeding depression became evident. Today, assisted reproduction and biotechnology allow breeders to design and direct the reproductive course, disseminate desired traits and hasten genetic improvement. Generation interval can be greatly reduced by combining artificial insemination, which is the oldest and most widely used assisted reproductive technology, with the more recent techniques, such as oestrus synchronization, superovulation, ovum pick up from immature females even out of breeding season, and in vitro embryo production and transfer. Furthermore, the sex and genetic make-up of the offspring can be selected by using sex-sorted sperm for insemination, marker-assisted selection, functional deletion or addition of specific genes to the offspring's genome, or somatic cell nuclear transfer for cloning. However, the poor success rates with some of these procedures have delayed their large-scale application which, in turn, has hindered the proper evaluation of their genetic impact. The potential genetic consequences of some of these approaches merit the same degree of diligent evaluation that is currently extended to the procedures used for overcoming their 'technical' inefficiencies.
过去，通过识别优良个体、让表现出所需性状的动物交配、持续培育相关动物以延续其优良性状以及在近亲繁殖衰退明显时进行杂交来对家畜进行遗传改良。如今，辅助生殖和生物技术使育种者能够设计和指导繁殖过程，传播所需性状并加速遗传改良。通过将人工授精（这是最古老且应用最广泛的辅助生殖技术）与诸如发情同步化、超数排卵、即使在非繁殖季节也能从未成熟雌性采集卵子、体外胚胎生产和移植等较新的技术相结合，可以大大缩短世代间隔。此外，通过使用经性别分选的精子进行授精、标记辅助选择、对后代基因组进行特定基因的功能缺失或添加，或通过体细胞克隆进行核移植，可以选择后代的性别和基因组成。然而，其中一些程序的成功率较低，延迟了它们的大规模应用，这反过来又阻碍了对其遗传影响的恰当评估。这些方法中的一些潜在遗传后果值得进行与目前用于克服其“技术”低效性的程序相同程度的认真评估。
