12 December 1998

Piglets are real babes for pork industry and research

A litter of 5 piglets born at the University of Queensland's Veterinary Science Farm at Pinjarra Hills on the wekend has important ramifications for both the viability of the Australian pork industry and international research into genetic engineering and cloning.

The litter is the result of microscopic five-to six-day-old embryos transferred to a sow after having been frozen for four weeks.

The sow is a 200kg, two-and-a-half year old crossbred Large White and Landrace from the University's farm piggery. She was selected after already having produced several normal litters.

The piglets were the first born in Australia using a new technique involving special culture of the embryos before freezing by an ultra-rapid method called vitrification used by a team from the University's School of Veterinary Science and Animal Production.

A second litter, where the embryos were collected and frozen using the same method at between three and four days old, is due in January and, if they are born alive, will be a world first using this simple technique.

At this early stage the cells which form the embryo still have what is known as a zona or shell around them, which protects them from viral infections, as well as allowing washing to remove other infectious agents. Another safeguard against exotic diseases involves artificial insemination using disease-free sperm to fertilise the embryos.

Associate Professor Ranald Cameron, honorary research consultant at the University's School of Veterinary Science, headed the team which has been working on the project for three years.

He said piglets have been born from frozen embryos in the USA, Japan and Europe in recent years.

The project resulted from an 1995 Australian Research Council collaborative grant to the University and the Adelaide-based Bresagen Pty Ltd, a research and development company specialising in biological products, gene transfer and cloning.

The simple and inexpensive technique involves a special culture procedure to protect an embryo from temperature changes before it is plunged into liquid nitrogen, which results in its temperature dropping from 35 degrees celsius to minus 196 degrees celsius in a matter of seconds.

The embryos are collected and transplanted surgically, with both the donors and recipient sow's oestrous cycle synchronised through the use of hormones.

The project, which has already attracted the interest of American breeding companies, has so far involved 10 implants, with three sows confirmed pregnant.

Associate Professor Cameron said it had the potential to solve many of the Australian pork industry's major handicaps in relation to the importation of new genetic material.

"Australia's strict quarantine regulations have prevented fresh genetic material from being imported because no safe storage method had previously been available," he said.
"Without such a method, embryos need to be implanted within eight hours after collection.

"The only cases of successful international embryo transfer have been between America and Britain through the use of high-speed aircraft. The new technique would allow the safe transfer of pig embryos anywhere around the world, such as is done in the cattle and sheep industries.

"Australia urgently needs a fresh gene pool to be able to compete with the high meat quality and large litter producing strains of pigs being developed in America and Europe."

Through the technique, there is the potential to import "hyperprolific" breeds of pigs which produce litters of between 16 and 18 piglets from, for example, China.

These breeds are being used extensively in Britain, France and America for the study of reproduction and identifying gene markers that can be used in breeding programs for European breeds.

Professor Cameron said the method had the added advantage of allowing for the safe storage and preservation of valuable genetic material, previously only possible in Australia by having an isolated farm to keep out disease. "It will also assist in research involving genetic engineering and cloning by enabling embryo banks to be established in research laboratories," he said.

The University research team involved in the project is Associate Professor Cameron, Dr Luke Beebe, Professor Alan Blackshaw and research assistant Ann Higgins.

For further information, contact Associate Professor Cameron or Dr Beebe (telephone 336 55721 or 3365 5718 or 3878 3419).