Super dads or Surrogate sires’ are developed to broadcast desirable traits rapidly among the population of animals.
Drawbacks: Artificial Insemination
Practically artificial insemination in cow with sperm collected from elite bulls, has yielded cows that produces four times more milk. But hard to track down cows at the right stage of their reproductive cycle, in case of pigs it doesn’t work well because sperm often die in storage.
Super dads or Surrogate sires'
Gene-editing tool CRISPR-Cas9 was employed to disable a gene –NANOS2. This knocked-out gene can’t produce sperm, making them male sterile and ideal of surrogate sires. Sperm-producing stem cells from donor male is transplanted into surrogate sires/super dads.
Spermatogonial stem cell transplantation (SSCT)
Technique of transferring germline between donor and recipient males. Male mice, pigs, goats, and cattle harboring knockout alleles of the NANOS2 gene generated by CRISPR-Cas9 editing have testes that are testes that are germline ablated but otherwise structurally normal. SSCT with allogeneic donor stem cells led to sustained donor-derived spermatogenesis and natural fertility.
Advantages of Super dads / Surrogate sires
- Indigenous germ line ablated bucks carry the sperm of ‘elite’ bucks
- Instead of having one elite buck we would have thousands.
- It provides a transformative step change to disseminate ‘elite’ semen without changing the existing infrastructure.
Ledford H. 2019. Bull “super dads” are being engineered to produce sperm from another father. Nature 567: 292-293
Oatley, J.M., 2018. Recent advances for spermatogonial stem cell transplantation in livestock. Reproduction, fertility and Development, 30(1), pp.44-49.
Park, K.E., Kaucher, A.V., Powell, A., Waqas, M.S., Sandmaier, S.E., Oatley, M.J., Park, C.H., Tibary, A., Donovan, D.M., Blomberg, L.A. and Lillico, S.G., 2017. Generation of germline ablated male pigs by CRISPR/Cas9 editing of the NANOS2 gene. Sci Rep 10 (7): 40176.