Optimized sperm injection technologies for in vitro embryo production in cattle

这项研究的领域是牛的先进繁殖技术。精子注射技术（SIT），其中单个精子被注射到卵子中以实现体外受精，在世界各地的人类诊所中非常成功地用于治疗男性不育症。然而，由于许多原因，该程序尚未在牛中得到适当的开发，最重要的是，没有兴趣繁殖生育力或精液质量差的雄性。但这个领域正在发生变化，我们需要适应。性别分选精液，即允许分离Y和携带Y的精子从而允许在后代中预先选择性别的技术，是动物育种中的革命性技术。然而，该技术的效率仍然很低，并且由于分选操作（不是因为公牛生育力低下），它通常会导致精子样品具有低活力和活力。 这是精子注射技术的新应用之一。 我们建议开发的技术的另一个应用是在很小的年龄繁殖牛。最近已经开发了基因组选择技术，其允许高效地预测动物自出生以来的生产价值，而不需要等到动物成年并通过具有真实的生产（例如，如果它是奶牛，则是泌乳）来表达其遗传价值。但是从非常年轻的公牛身上收集的精液样本缺乏足够数量的活精子，小牛卵母细胞在体外受精后很难发育，这可以通过精子注射技术来克服。后者可以缩短世代间隔，加快遗传进展的速度。我们相信这项技术的发展将有助于加拿大乳制品行业在遗传学和辅助生殖技术方面保持目前的领先地位。

The field of this proposed research is advanced reproduction technologies in cattle. Sperm injection technologies (SIT), in which a single sperm is injected inside an egg to achieve fertilization in vitro, are very successfully used to treat male infertility in human clinics around the world. However, the procedure has not been properly developed in cattle for a number of reasons, most important, there was no interest in reproducing males with poor fertility or semen quality. But the field is changing and we need to adapt. Sex-sorted semen, i.e. the technology that allows separating Y and Y-bearing spermatozoa thereby allowing pre-selection of gender in the progeny is a revolutionary technology in animal breeding. However, the efficiency of the technology is still low and it can often result in sperm samples that have low motility and viability as a result of the sorting manipulations (not because the bull is subfertile). This is one of the new applications for sperm injection technologies. Another application of the technology we propose to develop is for the reproduction of cattle at very young ages. Genomic selection technologies have been recently developed that allow predicting with high efficiency the production value of an animal since birth, without needing to wait until the animal is adult and expresses its genetic value by having a real production, e.g. a lactation if it's a dairy cow. But semen samples collected from very young bulls lack enough numbers of viable sperm and calf oocytes have difficulties to develop after in vitro fertilization that may be overcome through sperm injection technologies. The later would allow shortening the generation interval and accelerate the rate of genetic progress. We believe the development of this technology will help the Canadian Dairy Industry remain in its current leadership position in terms of genetics and assisted reproduction technologies.