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Gene sequencing of embryos.

C. McGehee

Abstract:

4
Gene sequencing of embryos.
C. McGehee*, R. Cockrum, D. Winston. Virginia Tech Blacksburg, VA.

Before 2009 it required nearly 5 years before the genetic merit of an individual animal was determined. Once genomics was introduced into national evaluations, genetic progress in the dairy industry rapidly increased. The genetic merit of an animal can be determined at a young age and is highly reliable due to the large reference population available. However, the majority of genetic gain has been achieved on the sire side, resulting in genetic lag of cows. One approach to increasing the genetic gain of females is through embryo genotyping. This technology allows producers to make more educated decisions on which embryos to implant. Genotyping embryos, therefore, increases genetic progress by increasing selection intensity. This technology can also identify embryonic defects and genetic recessives to reduce early embryonic loss. Two techniques can be used to acquire biopsies from embryos for genomic testing. The first method is blade biopsy, which can be used for embryos in the late-morula or blastocyst stage sampling cells from the trophectoderm. The second method is ideal for cleavage-stage or morula-stage embryos. This method utilizes a needle to aspirate cells from the embryo; it requires that enough cells be collected to complete gene testing but must ensure there are not too many taken that will compromise the continued development of the embryo. Because sufficient DNA cannot be obtained to conduct a SNP-chip genotyping, enzymatic pre-amplification of the biopsy is required. However, fertility of the genotyped embryos is still a concern. Single-cell gene sequencing is a technology that will be available in the future, which would increase the integrity of the embryos and further the genetic improvement of dairy cows.

Keywords: embryo, genomic selection, embryo biopsy.

Biography: I am currently an undergraduate at Virginia Tech studying dairy science with a science and pre-veterinary emphasis. My interest is in the fields of genetics and reproduction. Following my undergraduate program, I would like to attend graduate school for a Ph.D. in endocrinology and reproductive physiology. This past summer I was the semen processing and research intern for Select Sires Inc. From 2014 to 2017 I conducted research with�Mycoplasma bovis. My studies include locations that the organism can be isolated within the cow and around the farm and the best ways to control�M. bovis�in sand bedding.