Spermatogonial Stem Cell Transplantation: Insights and Outlook for Domestic Animals.

The demand for food will increase to an unprecedented level over the next 30 years owing to human population expansion, thus necessitating an evolution that improves the efficiency of livestock production. Genetic gain to improve production traits of domestic animal populations is most effectively achieved via selective use of gametes from animals deemed to be elite, and this principle has been the basis of selective breeding strategies employed by humans for thousands of years. In modern-day animal agriculture, artificial insemination (AI) has been the staple of selective breeding programs, but it has inherent limitations for applications in beef cattle and pig production systems. In this review, we discuss the potential and current state of development for a concept termed Surrogate Sires as a next-generation breeding tool in livestock production. The scheme capitalizes on the capacity of spermatogonial stem cells to regenerate sperm production after isolation from donor testicular tissue and transfer into the testes of a recipient male that lacks endogenous germline, thereby allowing the surrogate male to produce offspring with the donor haplotype via natural mating. This concept provides an effective selective breeding tool to achieve genetic gain that is conducive for livestock production systems in which AI is difficult to implement.