Embryonic Stem Cell-Based Selection for Dairy Cattle Breeding Programs

MEDHAT, M.; GOSZCZYNSKI, D.E.; ROSS, P.J.; CHENG, H.

Conferencia; Plant & Animal Genome Conference XXVII; 2019

In dairy cattle, sires can be selected based on genetic merit predicted from their daughter yield deviations at 5-7 years of age, or for dams predicted from their own yield deviation at 3 or more years of age, or based on predictions using their genomic information any time after conception. However, in conventional or genomic evaluation schemes, the generation interval cannot be less than two years, since the cow reaches maturity at approximately 15-18 months old and needs nine more months for gestation. The recent derivation in cattle of stable embryonic stem cells (ESCs) introduced the possibility of In Vitro Breeding (IVB). In IVB schemes, sperm and eggs would be produced by in vitro differentiation of genomically selected ESC lines, which would be used to produce a new generation of embryos by in vitro fertilization. One cycle of IVB, encompassing genomic selection and meiosis could take as little as 3-4 months, significantly shortening the generation interval. Furthermore, gametes derived from ESCs could be used to produce large numbers of embryos. Embryo transfer of IVB derived embryos could allow complete control of the genetic structure of the next generation, replacing the usual distribution of semen. An IVB strategy that utilizes these advantages was compared with a genomic breeding strategy (GB) under a typical USA-like dairy cattle situation. In IVB, the cost of proving bulls is no longer relevant and genetic gain can be accelerated by a factor of 7 due to the significant shortening of the generation interval. Once all the technologies required for IVB become commercially available, this approach is likely to become a powerful tool for genetic improvement.