Australians prove an ET process

摘要

From Australia comes news of the birth of several large litters of healthy piglets, raising hopes that a commercially viable method of embryo transfer (ET) using frozen embryos may at last be near. Rights to the technology have already been awardedand work is in progress to verify the results under farm conditions by the end of this year. Significantly, the embryos were no more than 4 days old when they began the process of preservation and transfer that resulted in the successful Australian farrowings. Being able to freeze such an early stage is called the gold standard because it opens the way to international transfers. The health protocol on importation in most countries will accept a 4-day embryo, recognising that this still has its shell orzona pellucida intact to provide a barrier against the entry of infectious agents. What is more the shell can be washed to remove any bacteria or viruses that may be attached. "No-one has frozen this early-stage embryo until now," comments Dr Ranald Cameron, from the research team in Australia based at the University of Queensland's school of veterinary science. "But its use will allow genetic material to be moved both farm to farm and internationally with the lowest possible risk of disease transmission as well as being cost-effective. Bringing in live pigs delivered by hysterectomy probably rates at about 6 on a scale of 1 to 10, where 10 is the greatest health risk. Semen is in the range of 3-4. These embryos would not rate above 1 by comparison. They also carry 100 percent of a genetic line whereas semen has only 50 percent."