A new study has shown that sterile male pigs, goats and mice can produce sperm containing genetic material from donor animals.
An international team involving researchers from CTLGH, the Roslin Institute, Washington State University, University of Maryland and Utah State University have shown that animals made infertile using gene-editing techniques can become fertile again after receiving stem cells from donor animals.
Published today in the Proceedings of the National Academy of Science, this technology has the potential to help improve the productivity of livestock in low- and middle-income countries and help the millions of families who rely on them for food and income.
Using surrogate sire technology, genetics from animals found to have desirable traits, like milk yield, heat tolerance, growth rate or resilience to a specific disease, could be introduced in livestock animals without farmers having to rely on selective breeding techniques, which can take decades to come to fruition.
This technology could also be used to safeguard genetic diversity and help preserve the genetic pool of indigenous populations of tropical livestock, whose genetics are in danger of being lost due to dwindling numbers.
Surrogate Sire technology
Surrogate sires are male animals that do not produce their own sperm, but are capable of producing sperm containing the genetic material of donor animals.
In this study, researchers used the gene-editing technique CRISPR on mice, pigs, goats and cattle embryos to remove the NANOS2 gene, which is specific to male fertility. The male animals that were born were sterile and lacked the ability to produce their own sperm, but were otherwise completely healthy.
The sterile pigs, goats and mice then received stem cells from male donors of the same species into their testes and started to produce normal healthy sperm derived from the donor animal.
The surrogate sire mice have successfully bred and fathered healthy offspring, which all carried the genes of the donor mice. The stem cells introduced into pigs and goats developed but these animals have not yet been bred.
Improving livestock productivity
It is estimated that farmers will need to produce 70 per cent more food by 2050 to feed the growing population. Demand for animal protein, including milk and eggs, is increasing, especially in low- and middle- income countries where stunting in children due to malnutrition is common.
This study provides a powerful proof of concept of how science can help improve food production. Professor Bruce Whitelaw, Principal of CTLGH, Interim Director of the Roslin Institute and co-author of the paper said:
“The Surrogate Sire project shows how advanced reproductive technologies can be used to offer transformative food production systems that could be of real benefit to farmer communities, providing increased security to those who rely on livestock for their way of living.”
Dr Simon Lillico, a CTLGH researcher based at Roslin Institute who also co-authored the paper agreed. He said:
“This development has potential application for genetic improvement of livestock in low- and middle-income countries, such as those with whom CTLGH operate, where small-holder livestock holdings are crucial for food security, nutrition and income generation.”
Professor Jon Oatley, reproductive biologist at Washington State University’s College of Veterinary Medicine led the research team and commented:
“With this technology, we can get better dissemination of desirable traits and improve the efficiency of food production. This can have a major impact on addressing food insecurity around the world.”
Challenging perceptions surrounding gene-edited animals
Researchers are aware that it will be some years before the benefits of surrogate sires can be realized. “Even if all science is finished, the speed at which this can be put into action in livestock production anywhere in the world is going to be influenced by societal acceptance and government policy,” said John Oatley.