Optimized sperm injection technologies for in vitro embryo production in cattle

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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.