9 November 2001

Picking right gene for the trait

Meddling with nature or the

future of livestock farming?

Scotland correspondent

Shelley Wright catches up

on latest developments in

animal breeding at the

Roslin Institute, Edinburgh

TRADITIONAL livestock breeding could be enhanced by genomics, a developing science that identifies genes responsible for specific traits.

Chris Haley, a senior researcher at Edinburghs Roslin Institute, says normal breeding selection by producers makes slow, but steady progress in genetic improvement.

"But genomics allows us to identify animals carrying desirable genes and breeding from these animals will give a permanent genetic improvement," he says.

A combination of robust pedigree data and genetic markers allows the gene controlling a specific trait to be identified in a breeding animal. The offspring can then be tested to see which have inherited the gene, with those animals used for subsequent breeding.

Offspring not carrying the favourable gene, such as high milk protein, can be removed from the breeding herd or flock.

"Traditionally there is a wait of three years until heifers calve and start milking to see whether they have inherited the high milk protein gene. Genomics just speeds up the whole process," he says.

Genomics has been developing over the past decade, and has been used most extensively in the pig industry, resulting in eradication of the halothane gene, which makes pigs susceptible to stress, says Dr Haley.

"A molecular test was developed to identify the gene and it is now used world-wide to ensure halothane-positive pigs are not used for breeding."

Another use of genomics has been to identify the RN gene in pigs reared to produce ham. Animals carrying the unfavourable copy of the gene yield as much as 8% less ham. "A test was developed and has made a big difference to the economics of ham production."

Although most work has been done in the pig industry, Dr Haley is confident developments in other livestock sectors will evolve.

Disease resistance is one key area. "Breeding more robust animals will become increasingly important in the future as routine use of antibiotics is phased out and public concern about the use of chemicals in animal production continues to mount," he says.

But developing blood or hair tests to identify specific genes is not something that happens overnight. From start to finish, the process could take up to 10 years, Dr Haley says.

Looking ahead, he predicts that in 20 years, British livestock producers could supplement their traditional stock selection skills with molecular tests to detect genes associated with meat quality, growth rate, fat deposition and resistance to some diseases. &#42

GENOMICS

&#8226 Evolving science.

&#8226 Fast genetic improvement.

&#8226 Disease resistance research.

GENOMICS

&#8226 Evolving science.

&#8226 Fast genetic improvement.

&#8226 Disease resistance research.