Fans of science fiction are familiar with the image. Strange creatures emerging fully grown from bubbling tanks, glassy-eyed, sinister and definitely up to no good. Clones.
Entertainment value aside, the sci-fi image of cloning unfortunately creates misunderstanding, mistrust and even fear among the public as they consider the application of cloning in meat and dairy production.
Twenty years ago, scientists introduced the world to Dolly the sheep – the first cloned mammal. Since then, cloning technology has offered significant potential for multiplying the very best genetics among livestock populations. Fear and misunderstanding remain, however, and cloning has remained a small contributor in livestock reproductive technology and genetic improvement.
One concern – that cloned animals would suffer from poor health and short lifespans – was partially addressed recently as scientists announced the continued health and vigor of four cloned ewes, derived from the same cell lines as Dolly. The four sheep, which now range from 7 to 9 years old, essentially are twins to Dolly, and to the ewe that produced the genetic material that created Dolly.
The research report, titled “Healthy ageing of cloned sheep,” was recently published in the journal Nature Communications.
While the technology involved in successfully cloning an animal is complex, the process itself is quite simple. Cloning is an assisted reproductive technology, along the lines of artificial insemination, embryo transfer and in-vitro fertilization.
The most common form of cloning is known as “somatic cell nuclear transfer,” according to the Biotechnology Innovation Organization (BIO). In this process, scientists begin with a tissue sample from the animal they intend to clone. In the laboratory, technicians culture somatic, or non-reproductive cells from the sample. Then they remove DNA from the somatic cells and transfer it to an oocyte, or egg cell, from which they have removed the original genetic material. The cell grows into an embryo over several days in an incubator, and the technicians transfer it to a recipient female using conventional embryo transfer.
After a normal gestation period, the recipient female gives birth to the cloned calf, lamb or piglet. The resulting animal is the same as an identical twin of the original, born at a later time. Clones are not genetically modified organisms in which scientists have manipulated genetic material or added genes from other species.
Read more about the cloning process and cloning safety from BIO.
The option of cloning the most desirable animals offers numerous potential benefits to livestock producers. These include.
- Dissemination of the most valued genetics, with improved opportunity for operations of any size to use of premium genetics.
- Improved animal health and productivity, food quality and consumer demand.
- Potential to leverage outstanding females beyond current possibilities. Rather than selling embryos from a top female, breeders could sell clones.
- Quicker response to supply chain signals.
- Continued availability of genetics from top breeding animals even after they are out of production.
- Cloning allows selection for a package of traits. Rather than improving one area such as carcass quality at the expense of others such as feed efficiency, cloning can reproduce genetics that produce the occasional animal that “does it all.”
While it has significant potential, cloning remains expensive and inefficient. Quoted in a CNN article about the cloned sheep, Michigan State University biotechnology professor Jose Cibelli says technicians need to transfer cloned embryos into about 10 recipient cows to produce one live birth. Cibelli is credited as the first scientist to clone a cow, which he accomplished a year after Dolly's birth.